I get the following question quite a bit... What do performance teams do?
Let me start by saying there are different types of performance teams. There are Perf Development Teams, Perf Test Teams, "Central" performance teams, and Product/Feature Performance teams.
Perf Development and Test Teams share a couple of functions in common;
Some things unique to Performance Developers are;
Some things unique to Performance Tests are;
The difference between central and product performance teams has more to do with the level of depth expected. Central teams handle large products like Windows and SQL can only cover so much of the product. Product performance teams and go in great depth on there components and may not look at the broader use. In my experience the best is combinations of the two working together.
So now to summarize the answer to "What to performance teams do?" In general the teams help set performance goals, monitor performance throughout the product release cycle, do targeted and adhoc investigations, build prototypes, and improve the product code all to support releasing a product that meets customer expectations.
(Quick aside... I've move to the Windows Virtual Machines Team)