...if by performance you want more velocity.
You can get a little more oomph by applying a stiffer striker (hammer) spring, a heavier striker, lighter valve springs, flow porting, etc...
All of these modifications will use more gas than stock. It will be noticeably louder, too

I've done multiple variations of the above mods with Crosmans and QB's, the .22's seem to benefit more from the extra gas than the .177 rifles do.
Good luck. If you do go inside and fix her up, let us know how it turns out.
-JC