Im running a wordpress site on amazon EC2 (m1.medium) .
Im using CDN serve files and using W3C total cache to increase performance ( i cannot use page cache because im serving dynamic content and using PHP sessions.
I am using mod_deflate to keep good performance.
Problem i have is that from time to time the server response time is very slow , looking at the server monitor I see no special problem CPU is under 40%
Sometimes first byte is sent after 1.5 seconds and sometimes it can go up to 6-8 seconds.
What can i do here ?