With the new launcher, I can load it up and get into the title screen just fine, but when I attempt to join a world (singleplayer or multiplayer) It gets stuck on the "Loading Terrain" phase, becomes unresponsive, and crashes. I've tried removing any resource packs I have.

I would put the crash report here, but I don't know how to access them. The old java launcher works for me, though.

I haven't tested this on any other version than an unmodified 1.11.2.