I did a quick test:
1) Back up history.dat
2) Replace Camino 2.0.3 stable release with G5 optimized build
3) Launch Camino
4) Quit Camino
5) Re-launch Camino
History disappeared, except for the most recent 13 URLs. I went back to the stable release and history.dat backup, and everything was ok again.
Maybe there's something weird about my system that's causing some kind of conflict, or maybe the other people who use it never check their history and thus haven't noticed (I don't check history very often myself). But it seems clear to me that the problem I'm having, whether or not anyone else has it, is related to your G5 optimized build.
I hope others with a G5 can check and see if it's just me, or if it affects them as well. I wouldn't be too surprised if it were just me; I have a lot of junk on my machine.