In theory you get more notifications about transfers and match results with more friends, but that is limited and you'd think wouldn't be a data or processing priority that would impact RAM usage. I have a similar # friends and haven't seen any slow down or memory hogging on Android.

Only the programmers would know though. Most likely just some inefficient little memory bug has snuck in most recent batch of code.

Edit: conceivably memory and processing could be more intense for FB friends than T11, which i think many of Al's are.