One of our primary focuses at Percona is performance. Let me make some statements on what is “performance.”
In doing so I will refer to two pieces of content:
- Carry Millsap’s talk “Performance Instrumentation: Beyond What You Do Now” 
- White Paper (by Peter and Baron) “Goal-Driven Performance Optimization” 
I highly recommend that you familiarize yourself with both of them.
Performance is about tasks and time.
We say that the system is performing well if it