I started to build in the newest snapshot. I put down blocks and they appear instantly, and I break them and they break, but then they disappear/reappear and slowly redo what I just did. It's rather annoying and it messes with my workflow.
When I interact with mobs, the mobs take a long time to go through the interaction. I ended up spawning a bunch of cats when I was only trying to get one because it took forever to spawn when I hit the spawn egg once. When I was dealing damage, mobs continued moving for a while before finally taking it