When I load an existing world in any of the 1.9 snapshots, the following weirdness happens: https://youtu.be/Q209FeSRFrE
The terrain models get scrambled and the game lags intensively. Some item models get affected aswell, like the trapped chest. There was a previous attempt to film it (15w35b), but the recording software gave up

P.S. I can generate new maps just fine, but as soon as I relog, it starts again