My game lags in single player mode, often to the point that it crashes. If it doesn't crash, it gets to so few FPS that when I right-click doors to close them, they close and then immediately open again, and when i right-click to place blocks, instead of placing one the game will place several... Usually only 2, but lately (and especially since the snapshot 12w24a) it will place 3. The most i've ever seen is 4 blocks placed by one click, that has only happened once.
I have tried to download the Optifine that everyone is talking about...all I can find is blogs about it and sites with possibly flesh-eat viruses. I may have ruined my computer in the last 10 minutes trying to download it.
My reader distance is already set to short, that used to help but since the snapshot it doesn't make any differance. I've taken off the clouds and basically everything else you can do from in-game to make it run better, and it just seems to be getting worse. In fact, since the update when I first load the level it's only about 5 chunks big and then immediately drops off into a giant abyss in ever direction. I have to wait several minutes for it to load a full level and replace the void, and when it does it moves me back to the spawn and takes away anything I have done. Also since the snapshot, animals and blocks will randomly freeze for an unspecified amount of time and I can run around but not interact with anything.
Someone please help - I love minecraft, but it's getting literally unplayable.