We compared the ray-tracing performance with the three kernels using the multi-threaded C-Ray. Again, the PAE kernel had not led to any major differences, but switching from 32-bit to 64-bit is where the real speed improvements can be found. The C-Ray finished in less than half the time with the 64-bit kernel compared to the two 32-bit kernels.
Using x86_64 Linux also led to a terrific speed-up with the Gcrypt library when looking at the CAMELLIA256-ECB cipher.
With GnuPG, there was also an improvement with the 64-bit kernel but not much of a difference between the non-PAE and PAE Ubuntu kernels.