Performance Optimisation

[Intex]

I've noticed over time, even without the addition of additional mods, that our website has become increasingly unresponsive to general page requests. It's not related to the physical hardware or bandwidth as it produces the same results when executed on the LAN where the server sits.

Can someone point me in the right direction to a thread which outlines the basic steps to take to improve vB performance. Maybe the general ways to optmiise the database, check for errors etc. Can I check for areas where load seems to be increasing based upon specific parts of the DB / pages being processed (maybe a debug mode)?

Any help appreciated.

Thanks