World is slow, and takes everything a minute to register

When I flip a lever, button, use pistons or drop/ pick up items, everything takes about a minute to register. Movement around is smooth and seems normal until you try to actually do something. Placing and breaking blocks is instant, but if it's a chest, it'll break, wait a bit then drop the items. this started happening today, and only on this one world, even after restarting my computer.