diff --git a/CMakeLists.txt b/CMakeLists.txt
index f7e23e9..4f86379 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -180,6 +180,7 @@ if (${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION} GREATER 3.5) # Need 3.6 or abo
       ",-google-runtime-int"
       ",-google-runtime-references"
       ",-modernize-loop-convert"
+      ",-performance-inefficient-string-concatenation"
       ",-readability-inconsistent-declaration-parameter-name"
       ",-readability-named-parameter"
       )
diff --git a/encfs/FileUtils.cpp b/encfs/FileUtils.cpp
index 58e91a9..35bc65b 100644
--- a/encfs/FileUtils.cpp
+++ b/encfs/FileUtils.cpp
@@ -465,7 +465,7 @@ bool saveConfig(ConfigType type, const string &rootDir,
 template <typename T>
 tinyxml2::XMLElement *addEl(tinyxml2::XMLDocument &doc,
                             tinyxml2::XMLNode *parent, const char *name,
-                            T value) {
+                            const T &value) {
   auto el = doc.NewElement(name);
   el->SetText(value);
   parent->InsertEndChild(el);
@@ -475,7 +475,7 @@ tinyxml2::XMLElement *addEl(tinyxml2::XMLDocument &doc,
 template <>
 tinyxml2::XMLElement *addEl<>(tinyxml2::XMLDocument &doc,
                               tinyxml2::XMLNode *parent, const char *name,
-                              Interface iface) {
+                              const Interface &iface) {
   auto el = doc.NewElement(name);
 
   auto n = doc.NewElement("name");
@@ -497,7 +497,7 @@ tinyxml2::XMLElement *addEl<>(tinyxml2::XMLDocument &doc,
 template <>
 tinyxml2::XMLElement *addEl<>(tinyxml2::XMLDocument &doc,
                               tinyxml2::XMLNode *parent, const char *name,
-                              std::vector<unsigned char> data) {
+                              const std::vector<unsigned char> &data) {
   string v = string("\n") + B64StandardEncode(data) + "\n";
   return addEl(doc, parent, name, v.c_str());
 }