Enable the performance-* clang-tidy checks
diff --git a/.clang-tidy b/.clang-tidy
index b8f74e9..fbf0b65 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -1,6 +1,6 @@
 ---
-Checks: 'modernize-use-nullptr,google-build-namespaces,google-build-explicit-make-pair,readability-function-size'
-WarningsAsErrors: 'modernize-use-nullptr,google-build-namespaces,google-build-explicit-make-pair,readability-function-size'
+Checks: 'modernize-use-nullptr,google-build-namespaces,google-build-explicit-make-pair,readability-function-size,performance-*'
+WarningsAsErrors: 'modernize-use-nullptr,google-build-namespaces,google-build-explicit-make-pair,readability-function-size,performance-*'
 CheckOptions:
   - key:    readability-function-size.StatementThreshold
     value:  '450'