when does connection pooling stop helping performance

Hey everyone, I've been mulling over connection pooling. We use it a ton, and it really did help smooth out our database load when we started. But I'm starting to wonder if there's a point where managing the pool itself takes too much effort, or when fighting over pooled connections actually slows things down instead of speeding them up. Has anyone run into this? When did you notice connection pooling starting to cause problems or give you less and less benefit for your app's speed?