Right now I have 1000 concurrent users online. But my site is very slow. I could have 8000 concurrent users, but the server can't handle the traffic, and I'm losing visitors.
My server is a VPS server:
Dedicated CPU 7.2GHz
The memory usage is way below the available resources. (right now 632 MB) What should i do? Should i configure the apache server? If yes, how? What about caching, maybe memcached?
This is a virtual server, built up from nodes, each node representing 600 Mhz cpu and 376MB ram.
I'm running a website on it built with php and mysql.