Sysprof
Profiling tool that helps in finding the functions in which a program uses most of its time
Useful resources
/ideas - Ideas for future improvements to sysprof.
Installation
Sysprof can be found in many recent distibutions or obtained from GNOME Git, inside the sysprof module:
git clone git://git.gnome.org/sysprof
You need to compile it using the kernel headers package provided by your distribution. Read then the Sysprof quickstart to set it up.