Here are some test results on a vps with apache and nginx
This is without a CDN and no minification.
DISC BASIC MODE
Without query string - 3.5 to 4 second page load time
With query string - 3.5 to 4 second page load time
DISC ENHANCED MODE
Without query string - 3.5 to 4 second page load time
With query string - 6 to 6.5 second page load time