diff --git a/M6502/HarteTest_6502/stdafx.h b/M6502/HarteTest_6502/stdafx.h
index 5a61706..e24a9d3 100644
--- a/M6502/HarteTest_6502/stdafx.h
+++ b/M6502/HarteTest_6502/stdafx.h
@@ -11,9 +11,11 @@
 #include <unordered_map>
 #include <vector>
 
-#define USE_BOOST_JSON
-//#define USE_NLOHMANN_JSON
-//#define USE_JSONCPP_JSON
+//#define TEST_JSON_PERFORMANCE
+
+#define USE_BOOST_JSON	// 32 seconds
+//#define USE_NLOHMANN_JSON	// 58 seconds
+//#define USE_JSONCPP_JSON	// 88 seconds
 
 #ifdef USE_BOOST_JSON
 #	include <boost/json.hpp>
diff --git a/M6502/HarteTest_6502/tests.cpp b/M6502/HarteTest_6502/tests.cpp
index 082249e..afe6136 100644
--- a/M6502/HarteTest_6502/tests.cpp
+++ b/M6502/HarteTest_6502/tests.cpp
@@ -40,6 +40,7 @@ int main() {
             const auto opcode_test = test_t(opcode_test_element);
 
             TestRunner runner(opcode_test);
+#ifndef TEST_JSON_PERFORMANCE
             const auto good = runner.check();
             if (!good) {
                 if (!opcode_bad) {
@@ -49,6 +50,7 @@ int main() {
                     opcode_bad = true;
                 }
             }
+#endif
         }
     }