WordPress automatically adds query strings to enqueued static resources like stylesheets and scripts. This shall remove them on production sites.

remove_query_strings.php

<?php

/** 
 * WordPress automatically adds query strings to enqueued static resources like stylesheets and scripts.
 * This is meant for caching reasons (e.g. if a script version changes, 
 * it should prevent the client to use a cached copy of the old one).
 * However, this feature can be omitted to improve site performance.
 */

function remove_query_strings_questionmark( $src ){
	$rqs = explode( '?ver', $src );
        return $rqs[0];
}

function remove_query_strings_ampersand( $src ){
	$rqs = explode( '&ver', $src );
        return $rqs[0];
}

// hook filters
add_filter( 'script_loader_src', 'remove_query_strings_questionmark', 15, 1 );
add_filter( 'style_loader_src', 'remove_query_strings_questionmark', 15, 1 );
add_filter( 'script_loader_src', 'remove_query_strings_ampersand', 15, 1 );
add_filter( 'style_loader_src', 'remove_query_strings_ampersand', 15, 1 );

Keep in mind it will fail Google font libraries and possibly other api loaders