Ubuntu 9.04 finally won a test when it came to the FFmpeg performance, but it was by a slim lead. Leopard took 33 seconds to convert an AVI file to an NTSC VCD with FFmpeg while 31 seconds (2 seconds faster) was needed for the Jaunty Jackalope.
The newer GCC 4.3 in Ubuntu 9.04 had performed much better than Mac OS X 10.5.6. The newest version of GCC in X Code is 4.2.1 while the latest stable version of GCC is now in fact GCC 4.4.0. GCC 4.4.0 can actually be found for Mac OS X with the HPC SourceForge project, but we were sticking with the stable version found in X Code, which is officially supported by Apple.
To not a lot of surprise, when compiling ImageMagick it too was faster when being built under Ubuntu.