Ways to optimize vBulletin post your solutions

If interesting make a list with diferents solutions to optimize the servers.
Mine

Server:
Dual Xeon 2.8 (Dual), 2Gb Ram and SCSI Ultra 320 without Raid
Fedora Core 2.
eAccelerator, MySQL 4.1 and PHP 4.2

Stats:
Number of Posts 1.232.221
Number of members 16.927
Online 500-800

vBulletin:
-Natural search instead off vBulletin search.
Boolean search OFF

-A plugin to disable search when load is high
https://vborg.vbsupport.ru/showthread.php?t=102882

-vBulletin cache ON with eAccelerator and cached keys of static data

-Index for ip field in post table.

Please post your solutions about caching and optimize vBulletin

Excuse my broken English.

[PennylessZ28]

Hey I wanna get in on some of this knowledge.

Server:
Operating system Linux 2.6.8-022stab070.9-enterprise
CPU AuthenticAMD, Dual Core AMD Opteron(tm) Processor 265

Running PHP 4.3.9 & Apache v2.0.52

I am curious about learning more on PHP 5 with ACP and why it would benfit my forum?

I was about to install eaccelerator but I'm pausing to learn more first.

What might I experince if I simply upgraded right this second to php5 with out knowing what I'm getting into? IE what problems might I encounter with compadiblity with vbulletin.

Are there changes that need to be made?

I should mention that I noticed in an above post, the statement about PLESk, I used to use CPANEL but for some reaosn I thought plesk would be great this time around. 2 weeks in and I'm wondering if it was wise.

[Paul M]

Personally, I would avoid php 5 atm - upgrade to 4.4.2 and install APC, not eaccelerator.

We use plesk (7.5.4) and it doesn't seem to be any worse than cpanel.

[Xorlev]

4.3.9 has security flaws...at least upgrade to 4.4.2.

Also, there is no problems between PHP 4/5 on vBulletin. The PHP devs did extremely well when they released PHP 5 as to not break functionality. 99% of scripts work out of the box from PHP 4 to PHP 5.

Paul M: Why wouldn't you recommend PHP 5.1? PHP 5 sucks, but PHP 5.1 works wonderfully. I've used it on production sites for quite a while with no problems.

Ew, Plesk.