[potatosareok]

Heap sizes 32gb+ can't use compressed pointers so don't forget about that bit of overhead. 48gb is just in that annoying zone where you need to go above 48gb heap to get real benefits of 32gb+ effecive heap.

But I only maintain EE apps on at most 10gb heaps, so I'm not hugely experienced with tuning this. All I can recommend is heap size and CMS thresholds (no G1 exp) set so that at steady state you don't end up hitting full GCs.