When I updated to the snapshot for the first time to check it out, immediately I noticed a strange input lag. It takes a fraction of a second for moving the mouse to do anything to my viewing angle, and the same goes for moving with WASD.
To test it i quickly moved my mouse around the mousepad in short bursts, and there was a noticeable lag, even a gap between when I stop moving the mouse and when my viewing angle changes.
It might not sound like much, but it makes the game unplayable.
I then went back to test in 1.8.8, and it worked perfectly, so it must be the snapshot specifically, and not just an issue on my end.
Still in 15w32c.