Lag in snapshot

Happened to me too mate. I think it's because the launcher opens a new window with the 13w16a game. This causes the severe lag. I dropped from 150fps in 1.5.1 to 20fps in 13w16a. REALLY BIG inconvenience. 😞

I can back this too.. Changing any of the settings doesn't seem to make ANY noticeable difference. A minor increase of a few FPS by lowering the render distance from normal to tiny, but hardly noticeable.

Duplicate of MC-13932