Memory usage unaccounted for?

Field data and caches report as very small, but there is the 247MB in this case in GC so I'm wondering what is causing bloat there. If I leave them running without resizing for a few days they'll be around ~95% and ES starts responding with timeouts etc.

Maybe I really do need more memory for the load, but it's unclear (to me) what the reason is for holding whatever is in GC in memory. I'm enabling doc_values on more fields to see if that helps much as well, it seems to but it continues to ramp up to ~90-95%.

As far as creating dumps go I'm probably screwed with AWS hosting it haha.