Vanilla Launcher eats memory. The linked images are with the launcher sitting at the login screen. It slowly eats memory until it hits over a gig when a GC occurs and it falls back down and repeats repeatedly. The max memory that it eventually settled at having allocated on my system was ~1.7gigs and after a GC event it was only using ~290megs of the allocated 1.7gigs that it was not releasing to the system.

The largest sizable growth appeared the be the int[] primitive arrays, however the char[] primitive arrays were fairly large as well while also growing at a fairly decent rate. Everything else seemed to be fairly ignorable in both growth rate and memory usage eating a combined total of less then 150megs.

Example of climbing memory usage with a forced GC from jVisualVM: VanillaLauncherAtLoginScreen1.png
#1 and #2 memory usage in jVisualVM: VanillaLauncherAtLoginScreen2.png

This is while using Oracles recently released Java8. Have not tested on Java7.