diff --git a/examples/210-Evt-EventListeners.cpp b/examples/210-Evt-EventListeners.cpp
index d1827807..f9113197 100644
--- a/examples/210-Evt-EventListeners.cpp
+++ b/examples/210-Evt-EventListeners.cpp
@@ -21,6 +21,10 @@ std::string ws(int const level) {
     return std::string( 2 * level, ' ' );
 }
 
+std::ostream& operator<<(std::ostream& out, Catch::Tag t) {
+    return out << "original: " << t.original << "lower cased: " << t.lowerCased;
+}
+
 template< typename T >
 std::ostream& operator<<( std::ostream& os, std::vector<T> const& v ) {
     os << "{ ";
@@ -119,31 +123,36 @@ void print( std::ostream& os, int const level, std::string const& title, Catch::
     os << ws(level+1) << "- aborting: " << info.aborting << "\n";
 }
 
-// struct TestCaseInfo {
-//     enum SpecialProperties{
-//         None = 0,
-//         IsHidden = 1 << 1,
-//         ShouldFail = 1 << 2,
-//         MayFail = 1 << 3,
-//         Throws = 1 << 4,
-//         NonPortable = 1 << 5,
-//         Benchmark = 1 << 6
-//     };
+//    struct Tag {
+//        StringRef original, lowerCased;
+//    };
 //
-//     bool isHidden() const;
-//     bool throws() const;
-//     bool okToFail() const;
-//     bool expectedToFail() const;
 //
-//     std::string tagsAsString() const;
+//    enum class TestCaseProperties : uint8_t {
+//        None = 0,
+//        IsHidden = 1 << 1,
+//        ShouldFail = 1 << 2,
+//        MayFail = 1 << 3,
+//        Throws = 1 << 4,
+//        NonPortable = 1 << 5,
+//        Benchmark = 1 << 6
+//    };
 //
-//     std::string name;
-//     std::string className;
-//     std::vector<std::string> tags;
-//     std::vector<std::string> lcaseTags;
-//     SourceLineInfo lineInfo;
-//     SpecialProperties properties;
-// };
+//
+//    struct TestCaseInfo : NonCopyable {
+//
+//        bool isHidden() const;
+//        bool throws() const;
+//        bool okToFail() const;
+//        bool expectedToFail() const;
+//
+//
+//        std::string name;
+//        std::string className;
+//        std::vector<Tag> tags;
+//        SourceLineInfo lineInfo;
+//        TestCaseProperties properties = TestCaseProperties::None;
+//    };
 
 void print( std::ostream& os, int const level, std::string const& title, Catch::TestCaseInfo const& info ) {
     os << ws(level  ) << title << ":\n"
@@ -154,10 +163,9 @@ void print( std::ostream& os, int const level, std::string const& title, Catch::
        << ws(level+1) << "- tagsAsString(): '"  << info.tagsAsString() << "'\n"
        << ws(level+1) << "- name: '"            << info.name << "'\n"
        << ws(level+1) << "- className: '"       << info.className << "'\n"
-       << ws(level+1) << "- tags: "             << info.tags << "\n"
-       << ws(level+1) << "- lcaseTags: "        << info.lcaseTags << "\n";
+       << ws(level+1) << "- tags: "             << info.tags << "\n";
     print( os, level+1 , "- lineInfo", info.lineInfo );
-    os << ws(level+1) << "- properties (flags): 0x" << std::hex << info.properties << std::dec << "\n";
+    os << ws(level+1) << "- properties (flags): 0x" << std::hex << static_cast<uint32_t>(info.properties) << std::dec << "\n";
 }
 
 // struct TestCaseStats {
diff --git a/include/internal/catch_interfaces_testcase.h b/include/internal/catch_interfaces_testcase.h
index b59b814d..d176b490 100644
--- a/include/internal/catch_interfaces_testcase.h
+++ b/include/internal/catch_interfaces_testcase.h
@@ -9,10 +9,12 @@
 #define TWOBLUECUBES_CATCH_INTERFACES_TESTCASE_H_INCLUDED
 
 #include <vector>
+#include <memory>
 
 namespace Catch {
 
     class TestSpec;
+    struct TestCaseInfo;
 
     struct ITestInvoker {
         virtual void invoke () const = 0;
@@ -24,6 +26,7 @@ namespace Catch {
 
     struct ITestCaseRegistry {
         virtual ~ITestCaseRegistry();
+        virtual std::vector<std::unique_ptr<TestCaseInfo>> const& getAllInfos() const = 0;
         virtual std::vector<TestCaseHandle> const& getAllTests() const = 0;
         virtual std::vector<TestCaseHandle> const& getAllTestsSorted( IConfig const& config ) const = 0;
     };
diff --git a/include/internal/catch_list.cpp b/include/internal/catch_list.cpp
index db88ff16..cd003433 100644
--- a/include/internal/catch_list.cpp
+++ b/include/internal/catch_list.cpp
@@ -38,14 +38,13 @@ namespace Catch {
             TestSpec testSpec = config.testSpec();
             std::vector<TestCaseHandle> matchedTestCases = filterTests(getAllTestCasesSorted(config), testSpec, config);
 
-            std::map<std::string, TagInfo> tagCounts;
+            std::map<StringRef, TagInfo> tagCounts;
             for (auto const& testCase : matchedTestCases) {
                 for (auto const& tagName : testCase.getTestCaseInfo().tags) {
-                    std::string lcaseTagName = toLower(tagName);
-                    auto countIt = tagCounts.find(lcaseTagName);
-                    if (countIt == tagCounts.end())
-                        countIt = tagCounts.insert(std::make_pair(lcaseTagName, TagInfo())).first;
-                    countIt->second.add(tagName);
+                    auto it = tagCounts.find(tagName.lowerCased);
+                    if (it == tagCounts.end())
+                        it = tagCounts.insert(std::make_pair(tagName.lowerCased, TagInfo())).first;
+                    it->second.add(tagName.original);
                 }
             }
 
@@ -71,16 +70,16 @@ namespace Catch {
 
     } // end anonymous namespace
 
-    void TagInfo::add( std::string const& spelling ) {
+    void TagInfo::add( StringRef spelling ) {
         ++count;
         spellings.insert( spelling );
     }
 
     std::string TagInfo::all() const {
-        size_t size = 0;
+        // 2 per tag for brackets '[' and ']'
+        size_t size =  spellings.size() * 2;
         for (auto const& spelling : spellings) {
-            // Add 2 for the brackes
-            size += spelling.size() + 2;
+            size += spelling.size();
         }
 
         std::string out; out.reserve(size);
diff --git a/include/internal/catch_list.h b/include/internal/catch_list.h
index eff8b09e..17df5355 100644
--- a/include/internal/catch_list.h
+++ b/include/internal/catch_list.h
@@ -23,10 +23,10 @@ namespace Catch {
     };
 
     struct TagInfo {
-        void add(std::string const& spelling);
+        void add(StringRef spelling);
         std::string all() const;
 
-        std::set<std::string> spellings;
+        std::set<StringRef> spellings;
         std::size_t count = 0;
     };
 
diff --git a/include/internal/catch_session.cpp b/include/internal/catch_session.cpp
index 87b52d44..a4d5c016 100644
--- a/include/internal/catch_session.cpp
+++ b/include/internal/catch_session.cpp
@@ -116,26 +116,9 @@ namespace Catch {
             TestSpec::Matches m_matches;
         };
 
-        void applyFilenamesAsTags(Catch::IConfig const& config) {
-            for (auto const& testCase : getAllTestCasesSorted(config)) {
-                // Yeah, sue me. This will be removed soon.
-                auto& testInfo = const_cast<TestCaseInfo&>(testCase.getTestCaseInfo());
-
-                std::string filename = testInfo.lineInfo.file;
-                auto lastSlash = filename.find_last_of("\\/");
-                if (lastSlash != std::string::npos) {
-                    filename.erase(0, lastSlash);
-                    filename[0] = '#';
-                }
-
-                auto lastDot = filename.find_last_of('.');
-                if (lastDot != std::string::npos) {
-                    filename.erase(lastDot);
-                }
-
-                auto tags = testInfo.tags;
-                tags.push_back(std::move(filename));
-                setTags(testInfo, tags);
+        void applyFilenamesAsTags() {
+            for (auto const& testInfo : getRegistryHub().getTestCaseRegistry().getAllInfos()) {
+                testInfo->addFilenameTag();
             }
         }
 
@@ -285,8 +268,9 @@ namespace Catch {
 
             seedRng( *m_config );
 
-            if( m_configData.filenamesAsTags )
-                applyFilenamesAsTags( *m_config );
+            if (m_configData.filenamesAsTags) {
+                applyFilenamesAsTags();
+            }
 
             // Create reporter(s) so we can route listings through them
             auto reporter = makeReporter(m_config);
diff --git a/include/internal/catch_stringref.cpp b/include/internal/catch_stringref.cpp
index 215feef3..ad26b34c 100644
--- a/include/internal/catch_stringref.cpp
+++ b/include/internal/catch_stringref.cpp
@@ -38,6 +38,13 @@ namespace Catch {
             && (std::memcmp( m_start, other.m_start, m_size ) == 0);
     }
 
+    bool StringRef::operator<(StringRef const& rhs) const noexcept {
+        if (m_size < rhs.m_size) {
+            return strncmp(m_start, rhs.m_start, m_size) <= 0;
+        }
+        return strncmp(m_start, rhs.m_start, rhs.m_size) < 0;
+    }
+
     auto operator << ( std::ostream& os, StringRef const& str ) -> std::ostream& {
         return os.write(str.data(), str.size());
     }
diff --git a/include/internal/catch_stringref.h b/include/internal/catch_stringref.h
index dc2e748c..9d5522a5 100644
--- a/include/internal/catch_stringref.h
+++ b/include/internal/catch_stringref.h
@@ -58,6 +58,8 @@ namespace Catch {
             return m_start[index];
         }
 
+        bool operator<(StringRef const& rhs) const noexcept;
+
     public: // named queries
         constexpr auto empty() const noexcept -> bool {
             return m_size == 0;
@@ -91,7 +93,6 @@ namespace Catch {
     auto operator += ( std::string& lhs, StringRef const& sr ) -> std::string&;
     auto operator << ( std::ostream& os, StringRef const& sr ) -> std::ostream&;
 
-
     constexpr auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
         return StringRef( rawChars, size );
     }
diff --git a/include/internal/catch_test_case_info.cpp b/include/internal/catch_test_case_info.cpp
index 7ea729fa..35a57e6c 100644
--- a/include/internal/catch_test_case_info.cpp
+++ b/include/internal/catch_test_case_info.cpp
@@ -20,27 +20,58 @@
 namespace Catch {
 
     namespace {
-        TestCaseInfo::SpecialProperties parseSpecialTag( std::string const& tag ) {
-            if( startsWith( tag, '.' ) ||
-                tag == "!hide" )
-                return TestCaseInfo::IsHidden;
-            else if( tag == "!throws" )
-                return TestCaseInfo::Throws;
-            else if( tag == "!shouldfail" )
-                return TestCaseInfo::ShouldFail;
-            else if( tag == "!mayfail" )
-                return TestCaseInfo::MayFail;
-            else if( tag == "!nonportable" )
-                return TestCaseInfo::NonPortable;
-            else if( tag == "!benchmark" )
-                return static_cast<TestCaseInfo::SpecialProperties>( TestCaseInfo::Benchmark | TestCaseInfo::IsHidden );
+        using TCP_underlying_type = uint8_t;
+        static_assert(sizeof(TestCaseProperties) == sizeof(TCP_underlying_type),
+                      "The size of the TestCaseProperties is different from the assumed size");
+
+        TestCaseProperties operator|(TestCaseProperties lhs, TestCaseProperties rhs) {
+            return static_cast<TestCaseProperties>(
+                static_cast<TCP_underlying_type>(lhs) | static_cast<TCP_underlying_type>(rhs)
+            );
+        }
+
+        TestCaseProperties& operator|=(TestCaseProperties& lhs, TestCaseProperties rhs) {
+            lhs = static_cast<TestCaseProperties>(
+                static_cast<TCP_underlying_type>(lhs) | static_cast<TCP_underlying_type>(rhs)
+            );
+            return lhs;
+        }
+
+        TestCaseProperties operator&(TestCaseProperties lhs, TestCaseProperties rhs) {
+            return static_cast<TestCaseProperties>(
+                static_cast<TCP_underlying_type>(lhs) & static_cast<TCP_underlying_type>(rhs)
+            );
+        }
+
+        bool applies(TestCaseProperties tcp) {
+            static_assert(static_cast<TCP_underlying_type>(TestCaseProperties::None) == 0,
+                          "TestCaseProperties::None must be equal to 0");
+            return tcp != TestCaseProperties::None;
+        }
+
+        TestCaseProperties parseSpecialTag( StringRef tag ) {
+            if( (!tag.empty() && tag[0] == '.')
+               || tag == "!hide"_sr )
+                return TestCaseProperties::IsHidden;
+            else if( tag == "!throws"_sr )
+                return TestCaseProperties::Throws;
+            else if( tag == "!shouldfail"_sr )
+                return TestCaseProperties::ShouldFail;
+            else if( tag == "!mayfail"_sr )
+                return TestCaseProperties::MayFail;
+            else if( tag == "!nonportable"_sr )
+                return TestCaseProperties::NonPortable;
+            else if( tag == "!benchmark"_sr )
+                return static_cast<TestCaseProperties>(TestCaseProperties::Benchmark | TestCaseProperties::IsHidden );
             else
-                return TestCaseInfo::None;
+                return TestCaseProperties::None;
         }
-        bool isReservedTag( std::string const& tag ) {
-            return parseSpecialTag( tag ) == TestCaseInfo::None && tag.size() > 0 && !std::isalnum( static_cast<unsigned char>(tag[0]) );
+        bool isReservedTag( StringRef tag ) {
+            return parseSpecialTag( tag ) == TestCaseProperties::None
+                && tag.size() > 0
+                && !std::isalnum( static_cast<unsigned char>(tag[0]) );
         }
-        void enforceNotReservedTag( std::string const& tag, SourceLineInfo const& _lineInfo ) {
+        void enforceNotReservedTag( StringRef tag, SourceLineInfo const& _lineInfo ) {
             CATCH_ENFORCE( !isReservedTag(tag),
                           "Tag name: [" << tag << "] is not allowed.\n"
                           << "Tag names starting with non alphanumeric characters are reserved\n"
@@ -51,90 +82,117 @@ namespace Catch {
             static size_t counter = 0;
             return "Anonymous test case " + std::to_string(++counter);
         }
+
+        StringRef extractFilenamePart(StringRef filename) {
+            size_t lastDot = filename.size();
+            while (lastDot > 0 && filename[lastDot - 1] != '.') {
+                --lastDot;
+            }
+            --lastDot;
+
+            size_t nameStart = lastDot;
+            while (nameStart > 0 && filename[nameStart - 1] != '/' && filename[nameStart - 1] != '\\') {
+                --nameStart;
+            }
+
+            return filename.substr(nameStart, lastDot - nameStart);
+        }
+
+        // Returns the upper bound on size of extra tags ([#file]+[.])
+        size_t sizeOfExtraTags(StringRef filepath) {
+            // [.] is 3, [#] is another 3
+            const size_t extras = 3 + 3;
+            return extractFilenamePart(filepath).size() + extras;
+        }
     }
 
     std::unique_ptr<TestCaseInfo>
         makeTestCaseInfo(std::string const& _className,
-                     NameAndTags const& nameAndTags,
-                     SourceLineInfo const& _lineInfo )
-    {
-        bool isHidden = false;
-
-        // Parse out tags
-        std::vector<std::string> tags;
-        std::string tag;
-        bool inTag = false;
-        for (char c : nameAndTags.tags) {
-            if( !inTag ) {
-                if (c == '[') {
-                    inTag = true;
-                }
-            } else {
-                if( c == ']' ) {
-                    TestCaseInfo::SpecialProperties prop = parseSpecialTag( tag );
-                    if( ( prop & TestCaseInfo::IsHidden ) != 0 )
-                        isHidden = true;
-                    else if( prop == TestCaseInfo::None )
-                        enforceNotReservedTag( tag, _lineInfo );
-
-                    // Merged hide tags like `[.approvals]` should be added as
-                    // `[.][approvals]`. The `[.]` is added at later point, so
-                    // we only strip the prefix
-                    if (startsWith(tag, '.') && tag.size() > 1) {
-                        tag.erase(0, 1);
-                    }
-                    tags.push_back( tag );
-                    tag.clear();
-                    inTag = false;
-                }
-                else
-                    tag += c;
-            }
-        }
-        if( isHidden ) {
-            tags.push_back( "." );
-        }
-
-        return std::make_unique<TestCaseInfo>(static_cast<std::string>(nameAndTags.name),
-                                              _className, tags, _lineInfo);
+                         NameAndTags const& nameAndTags,
+                         SourceLineInfo const& _lineInfo ) {
+        return std::make_unique<TestCaseInfo>(_className, nameAndTags, _lineInfo);
     }
 
-    void setTags( TestCaseInfo& testCaseInfo, std::vector<std::string> tags ) {
-        std::sort(begin(tags), end(tags));
-        tags.erase(std::unique(begin(tags), end(tags)), end(tags));
-        testCaseInfo.lcaseTags.clear();
-
-        for( auto const& tag : tags ) {
-            std::string lcaseTag = toLower( tag );
-            testCaseInfo.properties = static_cast<TestCaseInfo::SpecialProperties>( testCaseInfo.properties | parseSpecialTag( lcaseTag ) );
-            testCaseInfo.lcaseTags.push_back( lcaseTag );
-        }
-        testCaseInfo.tags = std::move(tags);
-    }
-
-    TestCaseInfo::TestCaseInfo( std::string const& _name,
-                                std::string const& _className,
-                                std::vector<std::string> const& _tags,
-                                SourceLineInfo const& _lineInfo )
-    :   name( _name.empty() ? makeDefaultName() : _name ),
+    TestCaseInfo::TestCaseInfo(std::string const& _className,
+                               NameAndTags const& _nameAndTags,
+                               SourceLineInfo const& _lineInfo):
+        name( _nameAndTags.name.empty() ? makeDefaultName() : _nameAndTags.name ),
         className( _className ),
-        lineInfo( _lineInfo ),
-        properties( None )
+        lineInfo( _lineInfo )
     {
-        setTags( *this, _tags );
+        StringRef originalTags = _nameAndTags.tags;
+        // We need to reserve enough space to store all of the tags
+        // (including optional hidden tag and filename tag)
+        auto requiredSize = originalTags.size() + sizeOfExtraTags(_lineInfo.file);
+        backingTags.reserve(requiredSize);
+        backingLCaseTags.reserve(requiredSize);
+
+        // We cannot copy the tags directly, as we need to normalize
+        // some tags, so that [.foo] is copied as [.][foo].
+        size_t tagStart = 0;
+        size_t tagEnd = 0;
+        bool inTag = false;
+        for (size_t idx = 0; idx < originalTags.size(); ++idx) {
+            auto c = originalTags[idx];
+            if (c == '[') {
+                assert(!inTag);
+                inTag = true;
+                tagStart = idx;
+            }
+            if (c == ']') {
+                assert(inTag);
+                inTag = false;
+                tagEnd = idx;
+                assert(tagStart < tagEnd);
+
+                // We need to check the tag for special meanings, copy
+                // it over to backing storage and actually reference the
+                // backing storage in the saved tags
+                StringRef tagStr = originalTags.substr(tagStart+1, tagEnd - tagStart - 1);
+                enforceNotReservedTag(tagStr, lineInfo);
+                properties |= parseSpecialTag(tagStr);
+                // When copying a tag to the backing storage, we need to
+                // check if it is a merged hide tag, such as [.foo], and
+                // if it is, we need to handle it as if it was [foo].
+                if (tagStr.size() > 1 && tagStr[0] == '.') {
+                    tagStr = tagStr.substr(1, tagStr.size() - 1);
+                }
+                // We skip over dealing with the [.] tag, as we will add
+                // it later unconditionally and then sort and unique all
+                // the tags.
+                internalAppendTag(tagStr);
+            }
+            (void)inTag; // Silence "set-but-unused" warning in release mode.
+        }
+        // Add [.] if relevant
+        if (isHidden()) {
+            internalAppendTag("."_sr);
+        }
+
+        // Sort and prepare tags
+        toLowerInPlace(backingLCaseTags);
+        std::sort(begin(tags), end(tags), [](Tag lhs, Tag rhs) { return lhs.lowerCased < rhs.lowerCased; });
+        tags.erase(std::unique(begin(tags), end(tags), [](Tag lhs, Tag rhs) {return lhs.lowerCased == rhs.lowerCased; }),
+                   end(tags));
     }
 
     bool TestCaseInfo::isHidden() const {
-        return ( properties & IsHidden ) != 0;
+        return applies( properties & TestCaseProperties::IsHidden );
     }
     bool TestCaseInfo::throws() const {
-        return ( properties & Throws ) != 0;
+        return applies( properties & TestCaseProperties::Throws );
     }
     bool TestCaseInfo::okToFail() const {
-        return ( properties & (ShouldFail | MayFail ) ) != 0;
+        return applies( properties & (TestCaseProperties::ShouldFail | TestCaseProperties::MayFail ) );
     }
     bool TestCaseInfo::expectedToFail() const {
-        return ( properties & (ShouldFail ) ) != 0;
+        return applies( properties & (TestCaseProperties::ShouldFail) );
+    }
+
+    void TestCaseInfo::addFilenameTag() {
+        std::string combined("#");
+        combined += extractFilenamePart(lineInfo.file);
+        internalAppendTag(combined);
     }
 
     std::string TestCaseInfo::tagsAsString() const {
@@ -142,18 +200,33 @@ namespace Catch {
         // '[' and ']' per tag
         std::size_t full_size = 2 * tags.size();
         for (const auto& tag : tags) {
-            full_size += tag.size();
+            full_size += tag.original.size();
         }
         ret.reserve(full_size);
         for (const auto& tag : tags) {
             ret.push_back('[');
-            ret.append(tag);
+            ret += tag.original;
             ret.push_back(']');
         }
 
         return ret;
     }
 
+    void TestCaseInfo::internalAppendTag(StringRef tagStr) {
+        backingTags += '[';
+        const auto backingStart = backingTags.size();
+        backingTags += tagStr;
+        const auto backingEnd = backingTags.size();
+        backingTags += ']';
+        backingLCaseTags += '[';
+        // We append the tag to the lower-case backing storage as-is,
+        // because we will perform the lower casing later, in bulk
+        backingLCaseTags += tagStr;
+        backingLCaseTags += ']';
+        tags.emplace_back(StringRef(backingTags.c_str() + backingStart, backingEnd - backingStart),
+                          StringRef(backingLCaseTags.c_str() + backingStart, backingEnd - backingStart));
+    }
+
 
     bool TestCaseHandle::operator == ( TestCaseHandle const& rhs ) const {
         return m_invoker == rhs.m_invoker
diff --git a/include/internal/catch_test_case_info.h b/include/internal/catch_test_case_info.h
index aa7353b2..5016e5d0 100644
--- a/include/internal/catch_test_case_info.h
+++ b/include/internal/catch_test_case_info.h
@@ -9,6 +9,7 @@
 #define TWOBLUECUBES_CATCH_TEST_CASE_INFO_H_INCLUDED
 
 #include "catch_common.h"
+#include "catch_stringref.h"
 #include "catch_test_registry.h"
 
 #include <string>
@@ -22,39 +23,54 @@
 
 namespace Catch {
 
+    struct Tag {
+        Tag(StringRef original_, StringRef lowerCased_):
+            original(original_), lowerCased(lowerCased_)
+        {}
+        StringRef original, lowerCased;
+    };
+
     struct ITestInvoker;
 
+    enum class TestCaseProperties : uint8_t {
+        None = 0,
+        IsHidden = 1 << 1,
+        ShouldFail = 1 << 2,
+        MayFail = 1 << 3,
+        Throws = 1 << 4,
+        NonPortable = 1 << 5,
+        Benchmark = 1 << 6
+    };
+
+
     struct TestCaseInfo : NonCopyable {
-        enum SpecialProperties{
-            None = 0,
-            IsHidden = 1 << 1,
-            ShouldFail = 1 << 2,
-            MayFail = 1 << 3,
-            Throws = 1 << 4,
-            NonPortable = 1 << 5,
-            Benchmark = 1 << 6
-        };
 
-        TestCaseInfo(   std::string const& _name,
-                        std::string const& _className,
-                        std::vector<std::string> const& _tags,
-                        SourceLineInfo const& _lineInfo );
-
-        friend void setTags( TestCaseInfo& testCaseInfo, std::vector<std::string> tags );
+        TestCaseInfo(std::string const& _className,
+                     NameAndTags const& _tags,
+                     SourceLineInfo const& _lineInfo);
 
         bool isHidden() const;
         bool throws() const;
         bool okToFail() const;
         bool expectedToFail() const;
 
+        // Adds the tag(s) with test's filename (for the -# flag)
+        void addFilenameTag();
+
+
         std::string tagsAsString() const;
 
         std::string name;
         std::string className;
-        std::vector<std::string> tags;
-        std::vector<std::string> lcaseTags;
+    private:
+        std::string backingTags, backingLCaseTags;
+        // Internally we copy tags to the backing storage and then add
+        // refs to this storage to the tags vector.
+        void internalAppendTag(StringRef tagString);
+    public:
+        std::vector<Tag> tags;
         SourceLineInfo lineInfo;
-        SpecialProperties properties;
+        TestCaseProperties properties = TestCaseProperties::None;
     };
 
     class TestCaseHandle {
diff --git a/include/internal/catch_test_case_registry_impl.cpp b/include/internal/catch_test_case_registry_impl.cpp
index 61f54afb..6891a53b 100644
--- a/include/internal/catch_test_case_registry_impl.cpp
+++ b/include/internal/catch_test_case_registry_impl.cpp
@@ -78,6 +78,10 @@ namespace Catch {
         m_invokers.push_back(std::move(testInvoker));
     }
 
+    std::vector<std::unique_ptr<TestCaseInfo>> const& TestRegistry::getAllInfos() const {
+        return m_infos;
+    }
+
     std::vector<TestCaseHandle> const& TestRegistry::getAllTests() const {
         return m_handles;
     }
diff --git a/include/internal/catch_test_case_registry_impl.h b/include/internal/catch_test_case_registry_impl.h
index 1f72cc0f..d6fa6e14 100644
--- a/include/internal/catch_test_case_registry_impl.h
+++ b/include/internal/catch_test_case_registry_impl.h
@@ -37,6 +37,7 @@ namespace Catch {
 
         virtual void registerTest( std::unique_ptr<TestCaseInfo> testInfo, std::unique_ptr<ITestInvoker> testInvoker );
 
+        std::vector<std::unique_ptr<TestCaseInfo>> const& getAllInfos() const override;
         std::vector<TestCaseHandle> const& getAllTests() const override;
         std::vector<TestCaseHandle> const& getAllTestsSorted( IConfig const& config ) const override;
 
diff --git a/include/internal/catch_test_spec.cpp b/include/internal/catch_test_spec.cpp
index 0292673a..6c63d4ce 100644
--- a/include/internal/catch_test_spec.cpp
+++ b/include/internal/catch_test_spec.cpp
@@ -43,9 +43,11 @@ namespace Catch {
     {}
 
     bool TestSpec::TagPattern::matches( TestCaseInfo const& testCase ) const {
-        return std::find(begin(testCase.lcaseTags),
-                         end(testCase.lcaseTags),
-                         m_tag) != end(testCase.lcaseTags);
+        return std::find_if(begin(testCase.tags),
+                            end(testCase.tags),
+                            [&](Tag const& tag) {
+                                return tag.lowerCased == m_tag;
+                            }) != end(testCase.tags);
     }
 
     bool TestSpec::Filter::matches( TestCaseInfo const& testCase ) const {
diff --git a/include/reporters/catch_reporter_junit.cpp b/include/reporters/catch_reporter_junit.cpp
index 5fd27218..27f7c1c1 100644
--- a/include/reporters/catch_reporter_junit.cpp
+++ b/include/reporters/catch_reporter_junit.cpp
@@ -48,12 +48,17 @@ namespace Catch {
             return std::string(timeStamp);
         }
 
-        std::string fileNameTag(const std::vector<std::string> &tags) {
+        std::string fileNameTag(std::vector<Tag> const& tags) {
             auto it = std::find_if(begin(tags),
                                    end(tags),
-                                   [] (std::string const& tag) {return tag.front() == '#'; });
-            if (it != tags.end())
-                return it->substr(1);
+                                   [] (Tag const& tag) {
+                                       return tag.original.size() > 0
+                                           && tag.original[0] == '#'; });
+            if (it != tags.end()) {
+                return static_cast<std::string>(
+                    it->original.substr(1, it->original.size() - 1)
+                );
+            }
             return std::string();
         }
     } // anonymous namespace
diff --git a/include/reporters/catch_reporter_xml.cpp b/include/reporters/catch_reporter_xml.cpp
index fa2ed0c7..d9a3cef3 100644
--- a/include/reporters/catch_reporter_xml.cpp
+++ b/include/reporters/catch_reporter_xml.cpp
@@ -312,7 +312,7 @@ namespace Catch {
             auto aliasTag = m_xml.scopedElement("Aliases");
             for (auto const& alias : tag.spellings) {
                 m_xml.startElement("Alias", XmlFormatting::Indent)
-                     .writeText(alias, XmlFormatting::None)
+                     .writeText(static_cast<std::string>(alias), XmlFormatting::None)
                      .endElement(XmlFormatting::Newline);
             }
         }
diff --git a/projects/SelfTest/Baselines/compact.sw.approved.txt b/projects/SelfTest/Baselines/compact.sw.approved.txt
index d7dfb5cc..6853df4e 100644
--- a/projects/SelfTest/Baselines/compact.sw.approved.txt
+++ b/projects/SelfTest/Baselines/compact.sw.approved.txt
@@ -1662,7 +1662,7 @@ StringManip.tests.cpp:<line number>: passed: Catch::replaceInPlace(s, "'", "|'")
 StringManip.tests.cpp:<line number>: passed: s == "didn|'t" for: "didn|'t" == "didn|'t"
 Misc.tests.cpp:<line number>: failed: false with 1 message: '3'
 Message.tests.cpp:<line number>: failed: false with 2 messages: 'hi' and 'i := 7'
-Tag.tests.cpp:<line number>: passed: testcase->tags, Catch::VectorContains(std::string("magic-tag")) && Catch::VectorContains(std::string(".")) for: { ".", "magic-tag" } ( Contains: "magic-tag" and Contains: "." )
+Tag.tests.cpp:<line number>: passed: tags, Catch::VectorContains("magic-tag"_catch_sr) && Catch::VectorContains("."_catch_sr) for: { ., magic-tag } ( Contains: magic-tag and Contains: . )
 StringManip.tests.cpp:<line number>: passed: splitStringRef("", ','), Equals(std::vector<StringRef>()) for: {  } Equals: {  }
 StringManip.tests.cpp:<line number>: passed: splitStringRef("abc", ','), Equals(std::vector<StringRef>{"abc"}) for: { abc } Equals: { abc }
 StringManip.tests.cpp:<line number>: passed: splitStringRef("abc,def", ','), Equals(std::vector<StringRef>{"abc", "def"}) for: { abc, def } Equals: { abc, def }
diff --git a/projects/SelfTest/Baselines/console.sw.approved.txt b/projects/SelfTest/Baselines/console.sw.approved.txt
index 9ed692cf..e8259948 100644
--- a/projects/SelfTest/Baselines/console.sw.approved.txt
+++ b/projects/SelfTest/Baselines/console.sw.approved.txt
@@ -12341,9 +12341,9 @@ Tag.tests.cpp:<line number>
 ...............................................................................
 
 Tag.tests.cpp:<line number>: PASSED:
-  REQUIRE_THAT( testcase->tags, Catch::VectorContains(std::string("magic-tag")) && Catch::VectorContains(std::string(".")) )
+  REQUIRE_THAT( tags, Catch::VectorContains("magic-tag"_catch_sr) && Catch::VectorContains("."_catch_sr) )
 with expansion:
-  { ".", "magic-tag" } ( Contains: "magic-tag" and Contains: "." )
+  { ., magic-tag } ( Contains: magic-tag and Contains: . )
 
 -------------------------------------------------------------------------------
 splitString
diff --git a/projects/SelfTest/Baselines/xml.sw.approved.txt b/projects/SelfTest/Baselines/xml.sw.approved.txt
index effb76f4..d57f0b86 100644
--- a/projects/SelfTest/Baselines/xml.sw.approved.txt
+++ b/projects/SelfTest/Baselines/xml.sw.approved.txt
@@ -1730,7 +1730,7 @@ Nor would this
       </Failure>
       <OverallResult success="false"/>
     </TestCase>
-    <TestCase name="A failing expression with a non streamable type is still captured" tags="[.][Tricky][failing]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="A failing expression with a non streamable type is still captured" tags="[.][failing][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <Expression success="false" type="CHECK" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
         <Original>
           &amp;o1 == &amp;o2
@@ -2510,7 +2510,7 @@ Nor would this
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
-    <TestCase name="Comparing function pointers" tags="[Tricky][function pointer]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="Comparing function pointers" tags="[function pointer][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <Expression success="true" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
         <Original>
           a
@@ -10985,7 +10985,7 @@ Message from section two
       </Section>
       <OverallResult success="true"/>
     </TestCase>
-    <TestCase name="StringRef at compilation time" tags="[StringRef][Strings][constexpr]" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
+    <TestCase name="StringRef at compilation time" tags="[constexpr][StringRef][Strings]" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
       <Section name="Simple constructors" filename="projects/<exe-name>/IntrospectiveTests/String.tests.cpp" >
         <OverallResults successes="5" failures="0" expectedFailures="0"/>
       </Section>
@@ -13709,13 +13709,13 @@ There is no extra whitespace here
     <TestCase name="When unchecked exceptions are thrown, but caught, they do not affect the test" tags="[!throws]" filename="projects/<exe-name>/UsageTests/Exception.tests.cpp" >
       <OverallResult success="false"/>
     </TestCase>
-    <TestCase name="Where the LHS is not a simple value" tags="[.][Tricky][failing]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="Where the LHS is not a simple value" tags="[.][failing][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <Warning>
         Uncomment the code in this test to check that it gives a sensible compiler error
       </Warning>
       <OverallResult success="false"/>
     </TestCase>
-    <TestCase name="Where there is more to the expression after the RHS" tags="[.][Tricky][failing]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="Where there is more to the expression after the RHS" tags="[.][failing][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <Warning>
         Uncomment the code in this test to check that it gives a sensible compiler error
       </Warning>
@@ -13724,7 +13724,7 @@ There is no extra whitespace here
     <TestCase name="X/level/0/a" tags="[Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <OverallResult success="true"/>
     </TestCase>
-    <TestCase name="X/level/0/b" tags="[Tricky][fizz]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="X/level/0/b" tags="[fizz][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <OverallResult success="true"/>
     </TestCase>
     <TestCase name="X/level/1/a" tags="[Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
@@ -14504,7 +14504,7 @@ loose text artifact
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
-    <TestCase name="parseEnums" tags="[Strings][enums]" filename="projects/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
+    <TestCase name="parseEnums" tags="[enums][Strings]" filename="projects/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
       <Section name="No enums" filename="projects/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
         <Expression success="true" type="CHECK_THAT" filename="projects/<exe-name>/IntrospectiveTests/ToString.tests.cpp" >
           <Original>
@@ -14861,10 +14861,10 @@ loose text artifact
     <TestCase name="shortened hide tags are split apart" filename="projects/<exe-name>/IntrospectiveTests/Tag.tests.cpp" >
       <Expression success="true" type="REQUIRE_THAT" filename="projects/<exe-name>/IntrospectiveTests/Tag.tests.cpp" >
         <Original>
-          testcase->tags, Catch::VectorContains(std::string("magic-tag")) &amp;&amp; Catch::VectorContains(std::string("."))
+          tags, Catch::VectorContains("magic-tag"_catch_sr) &amp;&amp; Catch::VectorContains("."_catch_sr)
         </Original>
         <Expanded>
-          { ".", "magic-tag" } ( Contains: "magic-tag" and Contains: "." )
+          { ., magic-tag } ( Contains: magic-tag and Contains: . )
         </Expanded>
       </Expression>
       <OverallResult success="true"/>
@@ -15050,7 +15050,7 @@ loose text artifact
       </Expression>
       <OverallResult success="true"/>
     </TestCase>
-    <TestCase name="string literals of different sizes can be compared" tags="[.][Tricky][failing]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
+    <TestCase name="string literals of different sizes can be compared" tags="[.][failing][Tricky]" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
       <Expression success="false" type="REQUIRE" filename="projects/<exe-name>/UsageTests/Tricky.tests.cpp" >
         <Original>
           std::string( "first" ) == "second"
diff --git a/projects/SelfTest/IntrospectiveTests/Tag.tests.cpp b/projects/SelfTest/IntrospectiveTests/Tag.tests.cpp
index 79657226..5120d8ed 100644
--- a/projects/SelfTest/IntrospectiveTests/Tag.tests.cpp
+++ b/projects/SelfTest/IntrospectiveTests/Tag.tests.cpp
@@ -42,6 +42,12 @@ TEST_CASE( "Tag alias can be registered against tag patterns" ) {
 }
 
 TEST_CASE("shortened hide tags are split apart") {
+    using Catch::StringRef;
     auto testcase = Catch::makeTestCaseInfo("", {"fake test name", "[.magic-tag]"}, CATCH_INTERNAL_LINEINFO);
-    REQUIRE_THAT(testcase->tags, Catch::VectorContains(std::string("magic-tag")) && Catch::VectorContains(std::string(".")));
+    // Transform ...
+    std::vector<StringRef> tags;
+    for (auto const& tag : testcase->tags) {
+        tags.push_back(tag.original);
+    }
+    REQUIRE_THAT(tags, Catch::VectorContains("magic-tag"_catch_sr) && Catch::VectorContains("."_catch_sr));
 }