diff --git a/include/Logger.h b/include/Logger.h
index e36e200..4a8ec69 100644
--- a/include/Logger.h
+++ b/include/Logger.h
@@ -51,10 +51,10 @@ namespace {
     // Keep in mind that every parameter you set will be applied only in the context of the source file you're in
     // It is an inherent feature as a **header-only** library
     static void setMaxLogLevel(int maxLogLevel_);
-    static void setMaxLogLevel(LogLevel maxLogLevel_);
+    static void setMaxLogLevel(const LogLevel &maxLogLevel_);
     static void setEnableColors(bool enableColors_);
     static void setPropagateColorsOnUserHeader(bool propagateColorsOnUserHeader_);
-    static void setPrefixLevel(PrefixLevel prefixLevel_);
+    static void setPrefixLevel(const PrefixLevel &prefixLevel_);
     static void setUserHeaderStr(const std::string &userHeaderStr_);
     static void setPrefixFormat(const std::string &prefixFormat_);
 
@@ -77,13 +77,13 @@ namespace {
 
     // Macro-Related Methods
     // Those intended to be called using the above preprocessor macros
-    Logger(LogLevel logLevel_, char const * fileName_, int lineNumber_);
+    Logger(const LogLevel &logLevel_, char const * fileName_, const int &lineNumber_);
     virtual ~Logger();
 
   protected:
 
     static void buildCurrentPrefix();
-    static void getFormattedUserHeaderStr(std::string &formattedUserHeaderBuffer_);
+    static void formatUserHeaderStr(std::string &strBuffer_);
 
     static void hookStreamBuffer();
     static std::string getLogLevelColorStr(const LogLevel &selectedLogLevel_);
diff --git a/include/implementation/Logger.impl.h b/include/implementation/Logger.impl.h
index 599dc2d..28fa139 100644
--- a/include/implementation/Logger.impl.h
+++ b/include/implementation/Logger.impl.h
@@ -28,7 +28,7 @@ namespace {
   void Logger::setMaxLogLevel(int maxLogLevel_) {
     Logger::setMaxLogLevel(static_cast<Logger::LogLevel>(maxLogLevel_));
   }
-  void Logger::setMaxLogLevel(LogLevel maxLogLevel_) {
+  void Logger::setMaxLogLevel(const LogLevel &maxLogLevel_) {
     _maxLogLevel_ = maxLogLevel_;
   }
   void Logger::setEnableColors(bool enableColors_) {
@@ -37,7 +37,7 @@ namespace {
   void Logger::setPropagateColorsOnUserHeader(bool propagateColorsOnUserHeader_) {
     _propagateColorsOnUserHeader_ = propagateColorsOnUserHeader_;
   }
-  void Logger::setPrefixLevel(PrefixLevel prefixLevel_) {
+  void Logger::setPrefixLevel(const PrefixLevel &prefixLevel_) {
     _prefixLevel_ = prefixLevel_;
   }
   void Logger::setUserHeaderStr(const std::string &userHeaderStr_) {
@@ -70,7 +70,7 @@ namespace {
   }
 
   // C-tor D-tor
-  Logger::Logger(LogLevel logLevel_, char const *fileName_, int lineNumber_) {
+  Logger::Logger(const LogLevel &logLevel_, char const *fileName_, const int &lineNumber_) {
 
     hookStreamBuffer(); // hook the stream buffer to an object we can handle
     if (logLevel_ != _currentLogLevel_) _isNewLine_ = true; // force reprinting the prefix if the verbosity has changed
@@ -92,14 +92,11 @@ namespace {
 
     if (_currentLogLevel_ > _maxLogLevel_) return;
 
-    { // guard
-//      std::lock_guard<std::mutex> guard(_loggerMutex_);
-      printFormat(fmt_str, std::forward<TT>(args)...);
-      if (not _disablePrintfLineJump_ and fmt_str[strlen(fmt_str) - 1] != '\n') {
+    Logger::printFormat(fmt_str, std::forward<TT>(args)...);
+    if (not _disablePrintfLineJump_ and fmt_str[strlen(fmt_str) - 1] != '\n') {
         _outputStream_ << std::endl;
         _isNewLine_ = true;
       }
-    } // guard
 
   }
   template<typename T> Logger &Logger::operator<<(const T &data) {
@@ -138,7 +135,7 @@ namespace {
     // Nothing else -> NONE level
     if( Logger::_prefixLevel_ == Logger::PrefixLevel::NONE ){
       if( not _userHeaderStr_.empty() ){
-        Logger::getFormattedUserHeaderStr(_currentPrefix_);
+        Logger::formatUserHeaderStr(_currentPrefix_);
         _currentPrefix_ += " "; // extra space
       }
       return;
@@ -197,7 +194,7 @@ namespace {
     // "{USER_HEADER}" -> User prefix can have doubled spaces and spaces on the left
     if( not _userHeaderStr_.empty() ){
       strBuffer = "";
-      Logger::getFormattedUserHeaderStr(strBuffer);
+      Logger::formatUserHeaderStr(strBuffer);
       LoggerUtils::replaceSubstringInsideInputString(_currentPrefix_, "{USER_HEADER}", strBuffer);
     }
 
@@ -218,11 +215,11 @@ namespace {
       _currentPrefix_ += ": ";
     }
   }
-  void Logger::getFormattedUserHeaderStr(std::string &formattedUserHeaderBuffer_) {
+  void Logger::formatUserHeaderStr(std::string &strBuffer_) {
     if( not _userHeaderStr_.empty() ){
-      if(_enableColors_ and _propagateColorsOnUserHeader_) formattedUserHeaderBuffer_ += getLogLevelColorStr(_currentLogLevel_);
-      formattedUserHeaderBuffer_ += _userHeaderStr_;
-      if(_enableColors_ and _propagateColorsOnUserHeader_) formattedUserHeaderBuffer_ += "\033[0m";
+      if(_enableColors_ and _propagateColorsOnUserHeader_) strBuffer_ += getLogLevelColorStr(_currentLogLevel_);
+      strBuffer_ += _userHeaderStr_;
+      if(_enableColors_ and _propagateColorsOnUserHeader_) strBuffer_ += "\033[0m";
     }
   }
   std::string Logger::getLogLevelColorStr(const LogLevel &selectedLogLevel_) {
diff --git a/include/implementation/LoggerUtils.h b/include/implementation/LoggerUtils.h
index 62d3027..64afeb6 100644
--- a/include/implementation/LoggerUtils.h
+++ b/include/implementation/LoggerUtils.h
@@ -70,17 +70,17 @@ namespace LoggerUtils{
   };
 
   //! String Utils
-  inline bool doesStringContainsSubstring(std::string string_, std::string substring_, bool ignoreCase_ = false);
-  inline std::string padString(const std::string& inputStr_, unsigned int padSize_, const char& padChar = ' ');
+  inline bool doesStringContainsSubstring(const std::string &string_, const std::string &substring_, bool ignoreCase_ = false);
+  inline std::string padString(const std::string& inputStr_, const unsigned int &padSize_, const char& padChar = ' ');
   inline std::string toLowerCase(const std::string &inputStr_);
   inline std::string stripStringUnicode(const std::string &inputStr_);
   inline std::string repeatString(const std::string &inputStr_, int amount_);
-  inline void replaceSubstringInsideInputString(std::string &input_str_, const std::string &substr_to_look_for_, const std::string &substr_to_replace_);
   inline std::vector<std::string> splitString(const std::string& input_string_, const std::string& delimiter_);
   inline std::string formatString( const std::string& strToFormat_ ); // 0 args overrider
   template<typename ... Args> inline std::string formatString( const std::string& strToFormat_, const Args& ... args );
 
   inline void removeRepeatedCharInsideInputStr(std::string &inputStr_, const std::string &doubledChar_);
+  inline void replaceSubstringInsideInputString(std::string &input_str_, const std::string &substr_to_look_for_, const std::string &substr_to_replace_);
 
   // Hardware Utils
   inline int getTerminalWidth();
@@ -91,16 +91,19 @@ namespace LoggerUtils{
 namespace LoggerUtils{
 
 // String Utils
-  inline bool doesStringContainsSubstring(std::string string_, std::string substring_, bool ignoreCase_){
+  inline bool doesStringContainsSubstring(const std::string &string_, const std::string &substring_, bool ignoreCase_){
     if(substring_.size() > string_.size()) return false;
     if(ignoreCase_){
-      string_ = toLowerCase(string_);
-      substring_ = toLowerCase(substring_);
+      if(toLowerCase(string_).find(toLowerCase(substring_)) != std::string::npos){
+        return true;
+      }
+    }
+    else if(string_.find(substring_) != std::string::npos){
+      return true;
     }
-    if(string_.find(substring_) != std::string::npos) return true;
-    else return false;
+    return false;
   }
-  inline std::string padString(const std::string& inputStr_, unsigned int padSize_, const char& padChar){
+  inline std::string padString(const std::string& inputStr_, const unsigned int &padSize_, const char& padChar){
     std::string outputString;
     int padDelta = int(inputStr_.size()) - int(padSize_);
     while( padDelta < 0 ){