Many of us deal with MySQL databases that are accessed exclusively via Perl. If performance isn't up to expectations, Perl can get blamed. To make matters worse, some of us get little or no DBA support when dealing with MySQL performance. ("You're not using Oracle|SQL Server? You're on your own.")
- MySQL Performance Tuning: How to Write Efficient MySQL Applications
- MySQL Performance Tuning: Making sure your MySQL server flies
There's stuff in here that can save you hours of pouring over the docs.
The author also has a presentation on Building Maintainable and Fault-Tolerant MySQL Applications with Perl.