@Withering: I suspect this is a mod-related issue. As far as I know, one of the mods has a memory leak, can't quite remember which one though. Also: have you tried turning on save file compression? It's almost a must with some of the bigger mods; should really be set by them to begin with.
(If you want to use 2048, you'll need to replace the jre the game ships with with a 64-bit version. But you shouldn't need that much, and if there's indeed a memory leak, that's only a bandaid solution.)