I just moved my site to VPS here and tested the site on GTMetrix, the result is the site is slow. The problem seems because slow data rate transfer http://prntscr.com/h65zww You can see the first download, the site's html, took really long time.

On a peak time my site have 500+ active users on Analytics, but now only left 300+, my ranks are fine, so it seems because of connection problem. My site's using W3TC so although I have a lot of visitors the resource usage is low.

How can I solve this problem? Thanks