frangarcj has released an app called Oclock which is an overclocking app for the PSVita, heres more details:
Oclock Vita is a plugin developed by frangarcj and it is a simple overclocking plugin so you can get better performance out of your games. Nothing more, nothing less. It is created for the taiHEN framework so it is compatible with all taiHEN/HENkaku-running PS Vitas. Finally everyone gets access to overclocking!
Changelog for v1.2
◾Force clock settings on games that change clock on runtime
◾Fix left / right menu controls