How to improve my mac mini performance
I am surprised the suggestions have not piled up in the hour since you posted...
1-Best answer: Put an SSD on the Mini, it will feel way better than even maxing out RAM (I assume you already have a decent amount of RAM to start with, i.e., not less than 8GB and are running Mavericks)
If you've already done all of the above then anything else you might do will probably give you less of a performance jump.