I followed the instructions in a thread from last week, and installed the RPMs courtesy of Troels:
http://www.fsr.ku.dk/people/troels/rpms/php/
My only problem is this: I pulled up a page with phpinfo() on 10 minutes ago using PHP 3, and it came up fast, as if it were a plain-text page. After installed PHP 4, I pulled up the same page, and the phpinfo() took long enough to appear that I assumed it wasn't working. I was about to go try the RPM again when suddenly the phpinfo stuff appeared on the page.
Why is this? Is a manual install (tar files) going to be better? Or is it only slow the first time the module is used (it does seem a little faster on reloads)? Any advice appreciated.