I've had minecraft for three days now. Up until today the framerate had been a little slugish at times, but usually ok. Recently, the framerate plummeted to below 10 fps, even on tiny fog. I though the issue might have come from all the water movement on a canal system I made. So I tried a new world, and it was just as bad. The weird thing is that in this new world, the frame rate doesn't increase at all if i set the fog to tiny. It just stays exactly the same as far, whereas previously it would have dramatically increased the frame rate. I don't think I've changed anything, apart from updating java when the issue first arose.