Deebs provided me with a shell script to use, however I think it would be good to have this functionality either built in via the addon itself (and option to turn on or off), or a secondary addon linked the the XenForo cron.
What does it do?
When a search is performed, the index file must be loaded from the disk and then executed before it is loaded into the RAM, which may eventually time out and the index needs to be re-loaded. This adds maybe 1-2 seconds onto a search, where as a pre-loaded term (already loaded into the RAM) comes back within 10-20ms
Using this addon, a list of popular searches for your forum, or just a random word list in general could be used to keep those terms consistantly in the RAM, so your popular searches will always come back "instantly" opposed to a wait while the index is loaded and searched.