Tuning Apache-PHP-MySQL for speed [closed]

Question

I have leased VPS with 2GB mem.

Problem i have is that i have few joomla installations and server get in to very slow response if there is more than 30-50 users attached at same time.

Do you have any tips, books/tutorials/suggestions how to increase response time in this situation?

Pls. give me only very concrete and useful URLs, i would be very grateful.

In attachment i attached just part of htop view on that VPS

Answer 1

The easiest and cheapest thing you can do is to install a bytecode cache, e.g. APC. Thus, php does not need to process every file again and again.

If you're on Debian or Ubuntu this is as easy as apt-get install apc.