We have a fairly large project which used to run well on Unity 2.6. (Our current tests are only on Mac computers).
After conversion into 3.2 the project runs well on the Editor and even runs well when compiling with the “Development Build” option selected. But a normal build stalls on the Mac. In some simple scenes it works fine, but the important game scenes are the ones where the player stalls, and the stall is never on the same place so it is difficult to identify the problem.
It might be a problem with the Mac Builds. I have a similar issue with my project where the player runs fine on the web and as a windows exe, but the Mac Player appears to freeze.