MySQL Performance

Cache Performance Comparison
- see results section
- see section: So what my recommendations would be about using these caches for your application ?
- look at lots of user comments at the end of the post to learn more

How fast can you sort data with MySQL ?
Look at all these posts under benchmarks

Query Optimization
Web Tuesday , Zurich, Switzerland, November 2007
Presentation covers some basic rules of queries optimization for MySQL including application based tuning such as avoiding queries if you do not need their results etc.

mysql-performance-presentations