We recently upgraded perl on our 64-bit solaris systems and attempted to compile with 64-bit support. The main perl executable compiled OK, but when we started compiling modules things started failing. I think the first program to start throwing errors was expat for XML::Parser.

We decided to back up and take the safe route and go 32-bit because I didn't think there would be a noticeable difference. Maybe I was wrong here? It's solaris vs. intel, but maybe we would have seen a performance improvement? We may never know. Interesting to read about your results.