diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index 8939fa859..54e641879 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -112,7 +112,7 @@ struct Filepointer {
 };
 
 namespace {
-    const std::set<std::string> whitelist = { "clearerr", "feof", "ferror", "fgetpos", "ftell", "setbuf", "setvbuf", "ungetc", "ungetwc" };
+    const std::unordered_set<std::string> whitelist = { "clearerr", "feof", "ferror", "fgetpos", "ftell", "setbuf", "setvbuf", "ungetc", "ungetwc" };
 }
 
 void CheckIO::checkFileUsage()
diff --git a/lib/checkmemoryleak.cpp b/lib/checkmemoryleak.cpp
index b518fb659..0aa9c4044 100644
--- a/lib/checkmemoryleak.cpp
+++ b/lib/checkmemoryleak.cpp
@@ -54,7 +54,7 @@ static const CWE CWE772(772U);  // Missing Release of Resource after Effective L
  * This list contains function names with const parameters e.g.: atof(const char *)
  * TODO: This list should be replaced by <leak-ignore/> in .cfg files.
  */
-static const std::set<std::string> call_func_white_list = {
+static const std::unordered_set<std::string> call_func_white_list = {
     "_open", "_wopen", "access", "adjtime", "asctime_r", "asprintf", "chdir", "chmod", "chown"
     , "creat", "ctime_r", "execl", "execle", "execlp", "execv", "execve", "fchmod", "fcntl"
     , "fdatasync", "fclose", "flock", "fmemopen", "fnmatch", "fopen", "fopencookie", "for", "free"
diff --git a/lib/library.cpp b/lib/library.cpp
index 50ad74780..154ab8ee2 100644
--- a/lib/library.cpp
+++ b/lib/library.cpp
@@ -1008,7 +1008,7 @@ bool Library::isnullargbad(const Token *ftok, int argnr) const
     if (!arg) {
         // scan format string argument should not be null
         const std::string funcname = getFunctionName(ftok);
-        const std::map<std::string, Function>::const_iterator it = functions.find(funcname);
+        const std::unordered_map<std::string, Function>::const_iterator it = functions.find(funcname);
         if (it != functions.cend() && it->second.formatstr && it->second.formatstr_scan)
             return true;
     }
@@ -1021,7 +1021,7 @@ bool Library::isuninitargbad(const Token *ftok, int argnr, int indirect, bool *h
     if (!arg) {
         // non-scan format string argument should not be uninitialized
         const std::string funcname = getFunctionName(ftok);
-        const std::map<std::string, Function>::const_iterator it = functions.find(funcname);
+        const std::unordered_map<std::string, Function>::const_iterator it = functions.find(funcname);
         if (it != functions.cend() && it->second.formatstr && !it->second.formatstr_scan)
             return true;
     }
@@ -1078,7 +1078,7 @@ const Library::ArgumentChecks * Library::getarg(const Token *ftok, int argnr) co
 {
     if (isNotLibraryFunction(ftok))
         return nullptr;
-    const std::map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
     if (it1 == functions.cend())
         return nullptr;
     const std::map<int,ArgumentChecks>::const_iterator it2 = it1->second.argumentChecks.find(argnr);
@@ -1189,7 +1189,7 @@ bool Library::isNotLibraryFunction(const Token *ftok) const
 bool Library::matchArguments(const Token *ftok, const std::string &functionName) const
 {
     const int callargs = numberOfArguments(ftok);
-    const std::map<std::string, Function>::const_iterator it = functions.find(functionName);
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(functionName);
     if (it == functions.cend())
         return (callargs == 0);
     int args = 0;
@@ -1259,7 +1259,7 @@ bool Library::formatstr_function(const Token* ftok) const
     if (isNotLibraryFunction(ftok))
         return false;
 
-    const std::map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
     if (it != functions.cend())
         return it->second.formatstr;
     return false;
@@ -1290,7 +1290,7 @@ Library::UseRetValType Library::getUseRetValType(const Token *ftok) const
 {
     if (isNotLibraryFunction(ftok))
         return Library::UseRetValType::NONE;
-    const std::map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
     if (it != functions.cend())
         return it->second.useretval;
     return Library::UseRetValType::NONE;
@@ -1332,7 +1332,7 @@ const Library::Function *Library::getFunction(const Token *ftok) const
 {
     if (isNotLibraryFunction(ftok))
         return nullptr;
-    const std::map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
     if (it1 == functions.cend())
         return nullptr;
     return &it1->second;
@@ -1343,7 +1343,7 @@ bool Library::hasminsize(const Token *ftok) const
 {
     if (isNotLibraryFunction(ftok))
         return false;
-    const std::map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it1 = functions.find(getFunctionName(ftok));
     if (it1 == functions.cend())
         return false;
     for (std::map<int, ArgumentChecks>::const_iterator it2 = it1->second.argumentChecks.cbegin(); it2 != it1->second.argumentChecks.cend(); ++it2) {
@@ -1372,28 +1372,28 @@ Library::ArgumentChecks::Direction Library::getArgDirection(const Token* ftok, i
 
 bool Library::ignorefunction(const std::string& functionName) const
 {
-    const std::map<std::string, Function>::const_iterator it = functions.find(functionName);
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(functionName);
     if (it != functions.cend())
         return it->second.ignore;
     return false;
 }
 bool Library::isUse(const std::string& functionName) const
 {
-    const std::map<std::string, Function>::const_iterator it = functions.find(functionName);
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(functionName);
     if (it != functions.cend())
         return it->second.use;
     return false;
 }
 bool Library::isLeakIgnore(const std::string& functionName) const
 {
-    const  std::map<std::string, Function>::const_iterator it = functions.find(functionName);
+    const  std::unordered_map<std::string, Function>::const_iterator it = functions.find(functionName);
     if (it != functions.cend())
         return it->second.leakignore;
     return false;
 }
 bool Library::isFunctionConst(const std::string& functionName, bool pure) const
 {
-    const std::map<std::string, Function>::const_iterator it = functions.find(functionName);
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(functionName);
     if (it != functions.cend())
         return pure ? it->second.ispure : it->second.isconst;
     return false;
@@ -1404,7 +1404,7 @@ bool Library::isFunctionConst(const Token *ftok) const
         return true;
     if (isNotLibraryFunction(ftok))
         return false;
-    const std::map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
+    const std::unordered_map<std::string, Function>::const_iterator it = functions.find(getFunctionName(ftok));
     return (it != functions.end() && it->second.isconst);
 }
 
diff --git a/lib/library.h b/lib/library.h
index 77a7f0d26..f8c983542 100644
--- a/lib/library.h
+++ b/lib/library.h
@@ -30,6 +30,8 @@
 #include <map>
 #include <set>
 #include <string>
+#include <unordered_map>
+#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -316,7 +318,7 @@ public:
     };
 
     const Function *getFunction(const Token *ftok) const;
-    std::map<std::string, Function> functions;
+    std::unordered_map<std::string, Function> functions;
     bool isUse(const std::string& functionName) const;
     bool isLeakIgnore(const std::string& functionName) const;
     bool isFunctionConst(const std::string& functionName, bool pure) const;
@@ -422,7 +424,7 @@ public:
 
     std::vector<std::string> defines; // to provide some library defines
 
-    std::set<std::string> smartPointers;
+    std::unordered_set<std::string> smartPointers;
     bool isSmartPointer(const Token *tok) const;
 
     struct PodType {
@@ -431,7 +433,7 @@ public:
         enum class Type { NO, BOOL, CHAR, SHORT, INT, LONG, LONGLONG } stdtype;
     };
     const struct PodType *podtype(const std::string &name) const {
-        const std::map<std::string, struct PodType>::const_iterator it = mPodTypes.find(name);
+        const std::unordered_map<std::string, struct PodType>::const_iterator it = mPodTypes.find(name);
         return (it != mPodTypes.end()) ? &(it->second) : nullptr;
     }
 
@@ -575,7 +577,7 @@ private:
     std::map<std::string, ExportedFunctions> mExporters; // keywords that export variables/functions to libraries (meta-code/macros)
     std::map<std::string, std::set<std::string> > mImporters; // keywords that import variables/functions
     std::map<std::string, int> mReflection; // invocation of reflection
-    std::map<std::string, struct PodType> mPodTypes; // pod types
+    std::unordered_map<std::string, struct PodType> mPodTypes; // pod types
     std::map<std::string, PlatformType> mPlatformTypes; // platform independent typedefs
     std::map<std::string, Platform> mPlatforms; // platform dependent typedefs
     std::map<std::pair<std::string,std::string>, TypeCheck> mTypeChecks;
diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index d2792281e..ac812d136 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -1308,7 +1308,7 @@ void SymbolDatabase::createSymbolDatabaseEnums()
 
 void SymbolDatabase::createSymbolDatabaseIncompleteVars()
 {
-    const std::set<std::string> cpp20keywords = {
+    static const std::unordered_set<std::string> cpp20keywords = {
         "alignas",
         "alignof",
         "axiom",
@@ -1321,7 +1321,7 @@ void SymbolDatabase::createSymbolDatabaseIncompleteVars()
         "reflexpr",
         "requires",
     };
-    const std::set<std::string> cppkeywords = {
+    static const std::unordered_set<std::string> cppkeywords = {
         "asm",
         "auto",
         "catch",
@@ -5379,8 +5379,8 @@ namespace {
     "register", "return", "short", "signed", "sizeof", "static", "struct", "switch", "typedef", \
     "union", "unsigned", "void", "volatile", "while"
 
-    const std::set<std::string> c_keywords = { C_KEYWORDS, "restrict" };
-    const std::set<std::string> cpp_keywords = {
+    const std::unordered_set<std::string> c_keywords = { C_KEYWORDS, "restrict" };
+    const std::unordered_set<std::string> cpp_keywords = {
         C_KEYWORDS,
         "alignas", "alignof", "and", "and_eq", "asm", "bitand", "bitor", "bool", "catch", "char8_t", "char16_t",
         "char32_t", "class", "compl", "concept", "consteval", "constexpr", "constinit", "const_cast", "co_await",
diff --git a/lib/token.cpp b/lib/token.cpp
index f051af37c..bd47ea184 100644
--- a/lib/token.cpp
+++ b/lib/token.cpp
@@ -53,7 +53,7 @@ Token::~Token()
     delete mImpl;
 }
 
-static const std::set<std::string> controlFlowKeywords = {
+static const std::unordered_set<std::string> controlFlowKeywords = {
     "goto",
     "do",
     "if",
@@ -127,7 +127,7 @@ void Token::update_property_info()
     update_property_isStandardType();
 }
 
-static const std::set<std::string> stdTypes = { "bool"
+static const std::unordered_set<std::string> stdTypes = { "bool"
                                                 , "_Bool"
                                                 , "char"
                                                 , "double"
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 5666f91f8..2702a16e1 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -3369,15 +3369,15 @@ void Tokenizer::setVarId()
 
 // Variable declarations can't start with "return" etc.
 #define NOTSTART_C "NOT", "case", "default", "goto", "not", "return", "sizeof", "typedef"
-static const std::set<std::string> notstart_c = { NOTSTART_C };
-static const std::set<std::string> notstart_cpp = { NOTSTART_C,
+static const std::unordered_set<std::string> notstart_c = { NOTSTART_C };
+static const std::unordered_set<std::string> notstart_cpp = { NOTSTART_C,
                                                     "delete", "friend", "new", "throw", "using", "virtual", "explicit", "const_cast", "dynamic_cast", "reinterpret_cast", "static_cast", "template"
                                                   };
 
 void Tokenizer::setVarIdPass1()
 {
     // Variable declarations can't start with "return" etc.
-    const std::set<std::string>& notstart = (isC()) ? notstart_c : notstart_cpp;
+    const std::unordered_set<std::string>& notstart = (isC()) ? notstart_c : notstart_cpp;
 
     VariableMap variableMap;
     std::map<int, std::map<std::string, int> > structMembers;
@@ -9676,7 +9676,7 @@ void Tokenizer::findGarbageCode() const
 {
     const bool isCPP11 = isCPP() && mSettings->standards.cpp >= Standards::CPP11;
 
-    const std::set<std::string> nonConsecutiveKeywords{ "break",
+    static const std::unordered_set<std::string> nonConsecutiveKeywords{ "break",
         "continue",
         "for",
         "goto",
@@ -9757,7 +9757,7 @@ void Tokenizer::findGarbageCode() const
     }
 
     // Keywords in global scope
-    std::set<std::string> nonGlobalKeywords{"break",
+    static const std::unordered_set<std::string> nonGlobalKeywords{"break",
                                             "continue",
                                             "for",
                                             "goto",
@@ -10528,7 +10528,7 @@ void Tokenizer::simplifyCPPAttribute()
     }
 }
 
-static const std::set<std::string> keywords = {
+static const std::unordered_set<std::string> keywords = {
     "inline"
     , "_inline"
     , "__inline"
diff --git a/lib/tokenlist.h b/lib/tokenlist.h
index 2661e9b20..45456c532 100644
--- a/lib/tokenlist.h
+++ b/lib/tokenlist.h
@@ -25,6 +25,7 @@
 #include "token.h"
 
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 class Settings;
@@ -211,7 +212,7 @@ private:
     /** settings */
     const Settings* mSettings;
 
-    std::set<std::string> mKeywords;
+    std::unordered_set<std::string> mKeywords;
 
     /** File is known to be C/C++ code */
     bool mIsC;