diff --git a/apps/opencs/model/doc/savingstages.cpp b/apps/opencs/model/doc/savingstages.cpp
index 90d01b48e9..bf1db8030c 100644
--- a/apps/opencs/model/doc/savingstages.cpp
+++ b/apps/opencs/model/doc/savingstages.cpp
@@ -263,7 +263,7 @@ void CSMDoc::CollectionReferencesStage::perform(int stage, Messages& messages)
             std::deque<int>& indices = mState.getSubRecords()[cellId.getRefIdString()];
 
             // collect moved references at the end of the container
-            bool interior = cellId.getRefIdString()[0] != '#';
+            const bool interior = !cellId.startsWith("#");
             std::ostringstream stream;
             if (!interior)
             {
@@ -367,7 +367,7 @@ void CSMDoc::WriteCellCollectionStage::perform(int stage, Messages& messages)
         || references != mState.getSubRecords().end())
     {
         CSMWorld::Cell cellRecord = cell.get();
-        bool interior = cellRecord.mId.getRefIdString()[0] != '#';
+        const bool interior = !cellRecord.mId.startsWith("#");
 
         // count new references and adjust RefNumCount accordingsly
         unsigned int newRefNum = cellRecord.mRefNumCounter;
@@ -451,10 +451,9 @@ void CSMDoc::WritePathgridCollectionStage::perform(int stage, Messages& messages
     if (pathgrid.isModified() || pathgrid.mState == CSMWorld::RecordBase::State_Deleted)
     {
         CSMWorld::Pathgrid record = pathgrid.get();
-        std::string recordIdString = record.mId.getRefIdString();
-        if (recordIdString[0] == '#')
+        if (record.mId.startsWith("#"))
         {
-            std::istringstream stream(recordIdString.c_str());
+            std::istringstream stream(record.mId.getRefIdString());
             char ignore;
             stream >> ignore >> record.mData.mX >> record.mData.mY;
         }
diff --git a/apps/opencs/model/tools/gmstcheck.cpp b/apps/opencs/model/tools/gmstcheck.cpp
index 8b7390387e..858bc2c3ec 100644
--- a/apps/opencs/model/tools/gmstcheck.cpp
+++ b/apps/opencs/model/tools/gmstcheck.cpp
@@ -47,7 +47,7 @@ void CSMTools::GmstCheckStage::perform(int stage, CSMDoc::Messages& messages)
 
     // Checking type and limits
     // optimization - compare it to lists based on naming convention (f-float,i-int,s-string)
-    if (gmstIdString[0] == 'f')
+    if (gmst.mId.startsWith("f"))
     {
         for (size_t i = 0; i < CSMWorld::DefaultGmsts::FloatCount; ++i)
         {
@@ -74,7 +74,7 @@ void CSMTools::GmstCheckStage::perform(int stage, CSMDoc::Messages& messages)
             }
         }
     }
-    else if (gmstIdString[0] == 'i')
+    else if (gmst.mId.startsWith("i"))
     {
         for (size_t i = 0; i < CSMWorld::DefaultGmsts::IntCount; ++i)
         {
@@ -101,7 +101,7 @@ void CSMTools::GmstCheckStage::perform(int stage, CSMDoc::Messages& messages)
             }
         }
     }
-    else if (gmstIdString[0] == 's')
+    else if (gmst.mId.startsWith("s"))
     {
         for (size_t i = 0; i < CSMWorld::DefaultGmsts::StringCount; ++i)
         {
diff --git a/apps/opencs/model/world/pathgrid.cpp b/apps/opencs/model/world/pathgrid.cpp
index 78191d9b58..27d2b29600 100644
--- a/apps/opencs/model/world/pathgrid.cpp
+++ b/apps/opencs/model/world/pathgrid.cpp
@@ -9,7 +9,7 @@ void CSMWorld::Pathgrid::load(ESM::ESMReader& esm, bool& isDeleted, const IdColl
     load(esm, isDeleted);
 
     // correct ID
-    if (!mId.empty() && mId.getRefIdString()[0] != '#' && cells.searchId(mId) == -1)
+    if (!mId.empty() && !mId.startsWith("#") && cells.searchId(mId) == -1)
     {
         std::ostringstream stream;
         stream << "#" << mData.mX << " " << mData.mY;
diff --git a/apps/openmw/mwclass/misc.cpp b/apps/openmw/mwclass/misc.cpp
index 76bb7f2c29..51a4241cbf 100644
--- a/apps/openmw/mwclass/misc.cpp
+++ b/apps/openmw/mwclass/misc.cpp
@@ -243,7 +243,7 @@ namespace MWClass
 
     bool Miscellaneous::isSoulGem(const MWWorld::ConstPtr& ptr) const
     {
-        return Misc::StringUtils::ciStartsWith(ptr.getCellRef().getRefId().getRefIdString(), "misc_soulgem");
+        return ptr.getCellRef().getRefId().startsWith("misc_soulgem");
     }
 
 }
diff --git a/apps/openmw/mwclass/npc.cpp b/apps/openmw/mwclass/npc.cpp
index 04dcbe7334..27ca299ac1 100644
--- a/apps/openmw/mwclass/npc.cpp
+++ b/apps/openmw/mwclass/npc.cpp
@@ -1447,7 +1447,7 @@ namespace MWClass
 
     bool Npc::isClass(const MWWorld::ConstPtr& ptr, std::string_view className) const
     {
-        return Misc::StringUtils::ciEqual(ptr.get<ESM::NPC>()->mBase->mClass.getRefIdString(), className);
+        return ptr.get<ESM::NPC>()->mBase->mClass == className;
     }
 
     bool Npc::canSwim(const MWWorld::ConstPtr& ptr) const
diff --git a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
index 2e7581c469..c97ef43e7c 100644
--- a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
+++ b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
@@ -856,7 +856,7 @@ namespace MWMechanics
             for (const ESM::GameSetting& currentSetting : gameSettings)
             {
                 // Don't bother checking this GMST if it's not a sMagicBound* one.
-                if (!Misc::StringUtils::ciStartsWith(currentSetting.mId.getRefIdString(), "smagicbound"))
+                if (!currentSetting.mId.startsWith("smagicbound"))
                     continue;
 
                 // All sMagicBound* GMST's should be of type string
diff --git a/apps/openmw/mwrender/npcanimation.cpp b/apps/openmw/mwrender/npcanimation.cpp
index 7d2a9ec0a4..1025c21621 100644
--- a/apps/openmw/mwrender/npcanimation.cpp
+++ b/apps/openmw/mwrender/npcanimation.cpp
@@ -526,8 +526,7 @@ namespace MWRender
 
             addAnimSource(smodel, smodel);
 
-            if (!isWerewolf
-                && Misc::StringUtils::lowerCase(mNpc->mRace.getRefIdString()).find("argonian") != std::string::npos)
+            if (!isWerewolf && mNpc->mRace.contains("argonian"))
                 addAnimSource("meshes\\xargonian_swimkna.nif", smodel);
         }
         else
diff --git a/apps/openmw/mwworld/store.cpp b/apps/openmw/mwworld/store.cpp
index d3aa2a5ca9..866fa66440 100644
--- a/apps/openmw/mwworld/store.cpp
+++ b/apps/openmw/mwworld/store.cpp
@@ -153,7 +153,7 @@ namespace MWWorld
     {
         std::vector<const T*> results;
         std::copy_if(mShared.begin(), mShared.end(), std::back_inserter(results),
-            [prefix](const T* item) { return Misc::StringUtils::ciStartsWith(item->mId.getRefIdString(), prefix); });
+            [prefix](const T* item) { return item->mId.startsWith(prefix); });
         if (!results.empty())
             return results[Misc::Rng::rollDice(results.size(), prng)];
         return nullptr;
diff --git a/apps/openmw_test_suite/misc/test_stringops.cpp b/apps/openmw_test_suite/misc/test_stringops.cpp
index 7ef13b3541..2cfe53b1dd 100644
--- a/apps/openmw_test_suite/misc/test_stringops.cpp
+++ b/apps/openmw_test_suite/misc/test_stringops.cpp
@@ -171,6 +171,11 @@ namespace
         EXPECT_FALSE(ciStartsWith("foo", "foo bar"));
     }
 
+    TEST(MiscStringsCiStartsWith, should_be_case_insensitive)
+    {
+        EXPECT_TRUE(ciStartsWith("foo bar", "FOO"));
+    }
+
     TEST(MiscStringsFormat, string_format)
     {
         std::string f = "1%s2";
@@ -192,4 +197,39 @@ namespace
         EXPECT_EQ(Misc::StringUtils::format(f, view.substr(1, 1)), "122");
         EXPECT_EQ(Misc::StringUtils::format(f, view.substr(2)), "12");
     }
+
+    TEST(MiscStringsCiFind, should_return_zero_for_2_empty_strings)
+    {
+        EXPECT_EQ(ciFind(std::string_view(), std::string_view()), 0);
+    }
+
+    TEST(MiscStringsCiFind, should_return_zero_when_looking_for_empty_string)
+    {
+        EXPECT_EQ(ciFind("foo", std::string_view()), 0);
+    }
+
+    TEST(MiscStringsCiFind, should_return_npos_for_longer_substring)
+    {
+        EXPECT_EQ(ciFind("a", "aa"), std::string_view::npos);
+    }
+
+    TEST(MiscStringsCiFind, should_return_zero_for_the_same_string)
+    {
+        EXPECT_EQ(ciFind("foo", "foo"), 0);
+    }
+
+    TEST(MiscStringsCiFind, should_return_first_position_of_substring)
+    {
+        EXPECT_EQ(ciFind("foobar foobar", "bar"), 3);
+    }
+
+    TEST(MiscStringsCiFind, should_be_case_insensitive)
+    {
+        EXPECT_EQ(ciFind("foobar", "BAR"), 3);
+    }
+
+    TEST(MiscStringsCiFind, should_return_npos_for_absent_substring)
+    {
+        EXPECT_EQ(ciFind("foobar", "baz"), std::string_view::npos);
+    }
 }
diff --git a/components/esm/refid.cpp b/components/esm/refid.cpp
index 48a06ea6e5..27d3bb6d9d 100644
--- a/components/esm/refid.cpp
+++ b/components/esm/refid.cpp
@@ -44,6 +44,16 @@ namespace ESM
         return Misc::StringUtils::ciEqual(mId, rhs);
     }
 
+    bool RefId::startsWith(std::string_view prefix) const
+    {
+        return Misc::StringUtils::ciStartsWith(mId, prefix);
+    }
+
+    bool RefId::contains(std::string_view subString) const
+    {
+        return Misc::StringUtils::ciFind(mId, subString) != std::string_view::npos;
+    }
+
     const RefId RefId::sEmpty = {};
 }
 
diff --git a/components/esm/refid.hpp b/components/esm/refid.hpp
index 9a538146db..0d297cfb0f 100644
--- a/components/esm/refid.hpp
+++ b/components/esm/refid.hpp
@@ -29,6 +29,10 @@ namespace ESM
 
         bool empty() const { return mId.empty(); }
 
+        bool startsWith(std::string_view prefix) const;
+
+        bool contains(std::string_view subString) const;
+
         bool operator==(const RefId& rhs) const;
 
         bool operator==(std::string_view rhs) const;
diff --git a/components/misc/strings/algorithm.hpp b/components/misc/strings/algorithm.hpp
index 885b9e872e..f34801b8d3 100644
--- a/components/misc/strings/algorithm.hpp
+++ b/components/misc/strings/algorithm.hpp
@@ -176,6 +176,16 @@ namespace Misc::StringUtils
             return;
         str.replace(pos, substr.size(), with);
     }
+
+    inline std::string_view::size_type ciFind(std::string_view str, std::string_view substr)
+    {
+        if (str.size() < substr.size())
+            return std::string_view::npos;
+        for (std::string_view::size_type i = 0, n = str.size() - substr.size() + 1; i < n; ++i)
+            if (ciEqual(str.substr(i, substr.size()), substr))
+                return i;
+        return std::string_view::npos;
+    }
 }
 
 #endif