I wrote a post recently, mostly based in my 3 years experience working with osTicket, with most of the considerations to take in order to improve osTicket performance. You can read it here:
http://investigacionit.com.ar/optimizacion-de-bases-de-datos-mysql(http://investigacionit.com.ar/optimizacion-de-bases-de-datos-mysql)
You'll have to use the sidebar to translate it from spanish.
