vBulletin is one of the most popular commercial forum applications.

Here are some tips on how to improve the performance of your vBulletin forum:

•  Check your website using this online tool. It will give you valuable information on what modifications can be made in order to improve its performance.
•  Do not add extra plugins unless you really need them.
• Optimize your vBulletin database.
•  If you do have a lot of plugins, install vBulletin Plugin Accelerator.
•  You can install additional optimization plugins such as Compress Forum Templates , Template Cache System and Realtime Page Compressor.