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.
Environment
Windows 10 x64, Java 8u51 64-bit
Still in 15w32c.