All entities glitch out

I have a world, and it has several problems. First of all, the daylight cycle is on, but every 7 seconds about the sun keeps glitching back, causing the progression of time to be almost frozen. However, time does seem to pass, just extremely slowly. Secondly, all mobs move in small glitches. Instead of walking smoothly, they would move one block, pause, and move another one. Thirdly, when I dropped an item, it would just float there spinning around for about ten seconds, and then I would pick it back up again. Finally, I started a redstone clock using repeaters on one tick and redstone dust connecting them. I powered it using a wooden button, and it started. The wooden button wouldn't come unpressed, and when I broke it, the redstone dust and repeaters stayed powered. This also happened with a lever; where I flicked in on, then off. The redstone dust still stayed powered.