How do you maximize the performance of php application(s) such as phpBB? Let php use more memory? Let MySQL use more memory? What are the best ways to do this and how can I apply those methods?

I'd appreciate any help on this ...

Use MySQL query cache. Google it or search for it on these forums. KLaude left a nice link to it, however I can't find it at this time.

It increases performance substantially on high load php/mysql sites.

MySQL has its configuration file named my.conf. The file has the following entry:

query-cache-size = xxx M

Do I want to increase this number? Does this "query cache" for MySQL mean? If so, what would be the ideal amount of memory for query-cache-size?

Depends on how big your websites are, in the database. If you have several databases totalling 50MB, then I would set the cache to 70MB or more so you can go some time while keeping everything cached...probobly for several months.

This is the post I was talking about with a good HOWTO on this:
http://forums.servermatrix.com/viewtopic.p...ght=mysql+cache

Just curious.

Doesn't MySQL have configuration file template? So that you can just pick that template more suitable for a system that can use more memory? Isn't it better to do that way instead of changing parameters one by one manually?

Yes, MySQL has various templates for system memory size, and yes, it's best to use those.

Would you be kind to tell us how this can be done in more detail? Also my server has Celeron 2.4 and 1.5 GB of memory. What do you recommend me to do?

To increase performance I use mysql cache, zend optimizer and turck mmcache, vBull threads fly out of my server in around 0.006->0.010 seconds.

Ah, oh, this sounds like French to me(I took French in college, but only for 10 weeks). Can you explain this to me in English? Also if you have some input on my.conf(MySQL's configuration file), I'd appreciate it greatly.