I'm currently running apache and I've currently got memcahce set up running vbulletin
I'm thinking of swaping over to litespeed and installing xcache, to try and improve performance and response times.
If I install xchach am I better using that for the vbulletin datastore or should I stick with memcache?
What are people views of litespeed is it worth paying for other the performance benefits over apache? I'm thinking of that rather than ngix becuse I'm a newbie to managing a server and its seems the simplest solution without a steep learning curve.
Memcache and xcache are two different cache products. Memcache is used to store frequently use data objects, while xcache is used to store frequently used compiled PHP code. They can be used together on one vbulletin installation, although the overall performance effects of that depend on your particular situation.
Do you actually know where the bottleneck is? What sort of performance problems are you trying to solve? You need a lot of traffic before changing the web server (or even using a php cache) makes a difference.
If the server is a problem, you might want to consider Cherokee (web config!) and Lighttpd.
You might also consider paying someone to do it for you. It is what I would do myself if I had that much traffic (unfortunately not).