diff --git a/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1BatchUtilities.h b/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1BatchUtilities.h
index 37725e8595836e3e50cab82801c9bd426eb4e6dc..e4d84390dfa9cbc27dc09c87df2aeabaf612a4e2 100644
--- a/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1BatchUtilities.h
+++ b/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1BatchUtilities.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
 /////////////////////////////////////////////////////////////
@@ -30,7 +30,7 @@ public:
 	std::string getRandomConfigFile();
 
 	static void overlayATLASlogo();
-	static void overlayEventDetails(unsigned long runNumber, unsigned long eventNumber, std::string humanTimestamp);
+	static void overlayEventDetails(unsigned long runNumber, unsigned long eventNumber, const std::string& humanTimestamp);
 
 private:
 	std::vector<std::string> m_files;
diff --git a/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1FileUtilities.h b/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1FileUtilities.h
index d13e560466923592da97b6f3937bffd887419ed9..f0931493c4762e6132ebe3657ecafaebc1a90ddd 100644
--- a/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1FileUtilities.h
+++ b/graphics/VP1/VP1UtilsBase/VP1UtilsBase/VP1FileUtilities.h
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
 /////////////////////////////////////////////////////////////
@@ -51,7 +51,7 @@ public:
 		      int runNumber,
 		      int eventNumber,
 		      int timeStamp,
-              std::string textLabel = "");
+                      const std::string& textLabel = "");
 
   // **** Check if file exists ****
   static bool fileExistsAndReadable(const std::string&);
diff --git a/graphics/VP1/VP1UtilsBase/src/VP1BatchUtilities.cxx b/graphics/VP1/VP1UtilsBase/src/VP1BatchUtilities.cxx
index 84fcf8bfec0c043d568aaab7ee09d329d5c6bdb2..d667b6b91c4fd3338cdcfa28fbd61f82d8b186e0 100644
--- a/graphics/VP1/VP1UtilsBase/src/VP1BatchUtilities.cxx
+++ b/graphics/VP1/VP1UtilsBase/src/VP1BatchUtilities.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
 /////////////////////////////////////////////////////////////
@@ -24,9 +24,11 @@
 
 
 
-VP1BatchUtilities::VP1BatchUtilities(std::vector<std::string> files) : m_indexFile(0), m_lastIndexFile(0)
+VP1BatchUtilities::VP1BatchUtilities(std::vector<std::string> files) :
+  m_files(files),
+  m_indexFile(0),
+  m_lastIndexFile(0)
 {
-	m_files = files;
 	std::cout << "Got vector of " << files.size() << " items" << std::endl;
 	// Iterate and print values of vector
 	for(std::string n : m_files) {
@@ -90,7 +92,7 @@ void VP1BatchUtilities::overlayATLASlogo()
 
 // Overlay the event details to the image
 // it replaces the original image with a version having event details on it
-void VP1BatchUtilities::overlayEventDetails(unsigned long runNumber, unsigned long eventNumber, std::string humanTimestamp)
+void VP1BatchUtilities::overlayEventDetails(unsigned long runNumber, unsigned long eventNumber, const std::string& humanTimestamp)
 {
 
 	std::string nRun = std::to_string(runNumber);
diff --git a/graphics/VP1/VP1UtilsBase/src/VP1FileUtilities.cxx b/graphics/VP1/VP1UtilsBase/src/VP1FileUtilities.cxx
index 9c89cd4b61ad0f165cf68c44a5788be9d1f1e65e..6cb647a50e0d943f11bd0b179b0e58a69c143bb2 100644
--- a/graphics/VP1/VP1UtilsBase/src/VP1FileUtilities.cxx
+++ b/graphics/VP1/VP1UtilsBase/src/VP1FileUtilities.cxx
@@ -1,5 +1,5 @@
 /*
-  Copyright (C) 2002-2017 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2021 CERN for the benefit of the ATLAS collaboration
 */
 
 /////////////////////////////////////////////////////////////
@@ -68,7 +68,7 @@ void VP1FileUtilities::produceNewFile(const std::string& sourceFile,
 				      int runNumber,
 				      int eventNumber,
 				      int timeStamp,
-                      std::string textLabel)
+                                      const std::string& textLabel)
 {
   // Check if the sourceFile exists
   QString srcName(sourceFile.c_str());