Im having some serious problems with my page rendering speed on my dreamhost site. I've finally cut it down to this. I have a wordpress install that runs WPML and W3TC together and it seems they don't completely play nice. WPML is quite object/database intensive so without having the page cached before hand your talking about 4000-6000ms until the page even STARTS to load, but with the plugin it gets it down to about 300-700ms TTFB.
The issue I have is when I run the tests on webpagetest.org sometimes I get a normal TTFB and sometimes I don't. I believe the caching is not working correctly because the plugin is adding a language cookie preventing the page from caching. However, I can't figure out when or why, it seems completely random as to when it pulls up the cached version and when it doesn't, even after I "prime" the page!
This problem seems to go away when I disable WPML.
I have everything on the site optimized to a T, all caching enabled, my own CDN, minimal plugins, even made as many CSS sprites as I could to prevent extra HTTP calls. I also have PHP xcache enabled... very frustrated (*headache). I'm also on both a dreamhost VPN and a dreamhost mySQL VPN with ample memory/CPU! I've tried to talk to dreamhost about it, but as fellow dreamhost users you know the drill (Live chat says send a ticket --> send a ticket --> they basically reply back "we don't know, everything seems OK")
If someone with some caching / apache / backend experience is willing to give me a hand I'd be happy to pay $50-$60 for an hour or two of somebodys time. Even with this problem fixed my site is still pretty slow (for example, the wordpress admin backend takes 4-6 seconds to load every page ...)
Thank you in advance.
(When it caches properly: http://www.webpagetest.org/result/110915_GP_1KR2W/1/details/)
(When it doesn't: http://www.webpagetest.org/result/110915_DM_1KRAY/)