It's an antifeature for some M$ distrobutions.
Java, can eat alot of memory...
Windows uses cache-ing (essentially it will use a shit tonne of memory in order "save room" for future processes) Which doesn't really matter because another one of M$ anti-features is locking down the damned proces table in the first place!
Also, check to make sure your cpu is not overheating. That could cause a significant ammount of memory usage as well.
Might not be the case, but it would really help if you showed us your processing table and not your graph -.-