1.7 Crashing and frame issues

When the 1.7.2 update came out no matter what my settings were I got a steady 60 fps (which is fine) but in 1.6.4 I would get 400-500 fps, I can bear with the 60 fps but the game will crash every 5-10 minutes. Now with the 1.7.4 update when ever I go to a single player or multiplayer world the game automatically crashes.