vBulletin Performance - vBulletin Performance Tuning
vBulletin Performance Tuning
Unfortunately vBulletinautolinker.com autolinking image has a bit of a reputation for bloat, and poor performance is a recurring issue for many webmasters.
An overview of factors in performance tuning can be found at http://linuxbox.co.uk/vbulletin_performance_tuning.php . It briefly covers all the important points, and should give the moderately experienced admin enough pointers for further investigation.
Linuxbox.co.uk also offer a vBulletinautolinker.com autolinking image performance tuning/optimization service, charged at around $50 (30 GBP) depending on exact needs.