Minecraft became really choppy just looking or walking around after installing version 1.8. FPS was usually under 10, but sometimes up to 10-20 even though the max was 200+. Adjusting MC video options did not seem to help much. Reduced settings to the following –
Graphics: Fast, Smooth Lighting: Minimum, Clouds: off, Render Distance: 10 chunks, Max Framerate: 20 fps, View Bobbing: off, Particles: Minimal, Use Vsync: off.
Using the Windows task manager to increase the priority of the java process actually made the performance even worse - choppier.