Hi,
I've been having less than impressive php performance on my system ever since I installed it on a P2-350 with 128mb ram. Tinkered with all sorts of things and got marginal performance increases.
This morning I decided just to go for it and installed the zend php optimizer. (
http://www.zend.com/store/free_download.php?pid=13). Very, very nice installation script.
I didn't benchmark anything but it seems I've just increased the speed with which php pages are served by about 60%. Load difference on the server is minor. (ymmv of course). Squirrelmail now runs just about as fast as on the big servers of my ISP, mambo's frontpage loads decently now.
Didn't want to sound too much like an advertorial but I just had to share this.