If you are writing performance critical code for Linux, you should get Zoom. Period.

Note: I have no financial involvement in Zoom and do not receive commissions.

Most developers who have worked on the Mac will be familiar with Shark, the excellent profiling tool that Apple supplies to developers. Zoom is written by the same guys. Zoom is unfortunately not free ($199 USD), but if you are trying to optimize your code, it'll easily save you $200 worth of your time.