I've done a little bit of work recently to see how differently Perl performs on different operating systems compiled with different compilers and optimisation settings.
Running FreeBSD and Solaris on a Sun Ultra 40 (2 x AMD Opteron 2.8GHz CPUs, 4GB RAM), with Perl compiled with gcc and Sun's compiler (with and without optimisation), using SpamAssassin 3.1.5 as the test workload showed that Perl on FreeBSD compiled with 'gcc -O2' is distinctly faster than Perl on Solaris compiled with either gcc or Sun's compiler.
More details at:
http://jc.ngo.org.uk/blog/2006/09/05/day-58-of-60-developer-benchmarks-pt-3
and
http://jc.ngo.org.uk/blog/2006/09/06/day-59-of-60-developer-benchmarks-pt-4
