If you have the development tools installed, you can profile on  
macosx using shark (you don't even need to compile with -p). Invoke  
it from the command line on your executable as follows:

 > shark -i -1 -q ./yourexec.opt args

This will write a .mshark file in the directory that you can open  
with Shark.app.

 > open *.mshark

Best,

Daniel

P.S. I remember having problems if the executable did not run for  
long enough, shark couldn't take any samples.