I am trying to improve pagespeed of my website. When I test my site it tells "Compressing https://z-1-static.xx.fbcdn.net/rsrc.php/v2/yF/r/SQ7jeOqw5xW.js could save 188.3KiB (70% reduction)." I have W3 Total Cache installed and enabled gzip compression. But still it's showing the same issue. How can I edit compress this file as it's out of my control. Can anyone tell me how to solve this issue?