When optimizing page speed, you will often get an issue related to query strings ending with a question mark. This fixed it.
Add the following code snippet to your theme functions.php
file
/** THIS IS INTENDED TO IMPROVE THE POOR QUERY STRINGS ISSUE AT GT METRIX **/
function pu_remove_script_version( $src ){
return remove_query_arg( 'ver', $src );
}
add_filter( 'script_loader_src', 'pu_remove_script_version' );
add_filter( 'style_loader_src', 'pu_remove_script_version' );