One of the servers we've had for a while was running a bit slow.  After a few hours of searching, I've found out that one of the PHP scripts was running a mailer and it was just dragging the system down.  Although most of the load was through exim, our mailer, I found that apache was hogging up a bit of resources as well.  Since our server load was high and we were getting a decent number of visitors hitting on our vBulletin as well as a PHP lyrics script that I partially wrote for our Vietnamese lyrics website.  I went to search on how to optimize PHP scripts and I came up with eAccelerator.

The process of getting, untarring, building and installing took less than 20 minutes.  Of course, it may have taken a bit more in real time since I was eating and watching a movie at the same time.  I tried to put the eaccelerator.ini file inside of my /etc/php.d folder, but it didn't work out too well.  In fact, it didn't work at all :).  So I went with the putting it inside of my php.ini file.  Of course, I went with the default settings for my php.ini file:

[code lang="php"][eAccelerator] extension="eaccelerator.so" eaccelerator.shm_size="0" eaccelerator.cache_dir="/tmp/eaccelerator" eaccelerator.enable="1" eaccelerator.optimizer="1" eaccelerator.check_mtime="1" eaccelerator.debug="0" eaccelerator.filter="" eaccelerator.shm_max="0" eaccelerator.shm_ttl="0" eaccelerator.shm_prune_period="0" eaccelerator.shm_only="0" eaccelerator.compress="1" eaccelerator.compress_level="9"[/code]

I restarted apache and saw an immediate decrease in load!  It was averaging about 2.7 before and about 2.3-2.4 afterward.  I would venture to make a guess that eAccelerator does work and it did take some load off of the server when it needs it the most.  As to shm_size, I just set it to 0 and let the system take care of whatever size it needs.  I have a newer server that has a lot of RAM, so I gave it about 128MB of shared memory.  If the server becomes too slow for some reason, I'll start playing around with this number to see if there's an optimal size.