Yes and no. If the system’s memory load never gets over 100% with the current 16 gigs, adding more RAM and losing the benefits of dual channel memory will decrease memory performance. If the system’s memory load does go over the current 16 gigs, adding more RAM will increase performance in that situation as modern memory (no matter how slow it is) is faster than swapping memory in and out of the disk drive (no matter how fast it is). The question you have to answer is: Are you actually using more than the current 16 gigs? If not, adding more RAM will decrease performance. If you are, adding more RAM will only show a performance increase in those situations where the system needs more than 16 gigs, and you’ll have the performance decrease when you don’t.