For no reason at all, 1.7 lags like never before. Even on the title screen, the screen moves so slow and any buttons you click or move over have heavy amounts of lag.

In 1.6.4 downwards, I usually get 60fps easy.
In the first 1.7 snapshots, I had the bug where maximizing the screen gave you a lower fps then if you kept it a small window (MC-30158).
Now in the latest snapshots and the release of 1.7, I get around 0-10fps. Why?

I don't want to give up minecraft, but if this can't be fixed then I'm going to have to stick to 1.6 for now. Which is such a shame because 1.7 is an amazing update. :/