I'm having a weird issue with a vBulletin forum, on a 2х Xeon E5645 w/ 16GB RAM CentOS 6.3 x86_64 web server with cPanel and LiteSpeed; It takes too long to start loading...
When I tested it with webpagetest.org I saw that for every request there's a 3 second "Initial connection" delay, which I don't know why is happening. Here's a screenshot:
CPU Load is between 0.03 and 0.05, I've got several GB of free RAM, practical no I/O activity, and this delay can occur even with only one visitor on the forum.
Where do you suggest I start searching? What could be the reason for this kind of delay? I don't think it's the webserver, or the forum because there's another website on the server (total 2 sites) which is WordPress based, and has exactly the same issue with the 3 second initial connection delay. I believe it's OS related, but need a clue on where to start looking.