For the last months (without any significant change except modules and drupal core upgrades) I've been noticing that the First time to byte decreased from a not bad value (less than 300ms) to more than 2 - 3 seconds and I don't know why.
So I just moved from a shared hosting to a VPS but the First Time to Byte didn't change at all and I'm quite frustrated, could someone help me out please?
I'm using Boost, advagg, cache expiration and views content cache. Also I'm using Cloudflare as CDN but it didn't improve the performance either :(
I tried to analyze what's going on with the google developer tools (see attached image) but I cannot get enough information to figure out why so long waiting time.
Thanks in advance!