OFFLINE Local Multiplayer and extreme crashing/freezing/lagging in game

It started off as extreme lagging and elongated waiting times for the loading screen. Texture packs I have aren't seeming to work either and I have to wait over 30 minutes for my world to freeze and never load. I tried doing local-coop multiplayer (offline) with my partner and it continues to lag to the point I cannot mine a block, create a house or do anything. I cannot see their character move or mine on their screen. Split-screen also doesn't seem to work well, and local coop multiplayer seems to just lag when first joining the world. It's pretty much unplayable at this point for me.