Check this thread, I added some important information on performance enhancements. Also be sure to follow the guidance on IF you can do this to your system and not get kicked out your hosting platform.
Here
Likewise @twest has had a few fews discussions over performance enhancements, from changing swappyness, to limiting the IO per package as there's sometimes some nasty spikes in some conditions.
Many others have contributed too @AdamM has a great post on DB optimisation and using Releem for example.
Best bet is to try searching keywords that seem relevant and you'll find information.
