version using 100% of CPU

When I run the game and the new window pops up, it uses 100% of my CPU to the point where I can not play the game. This occurs right at the start up after I load my world. When I am in the game, it is so slow and glitchy that I end it after a few minutes. This is in a private single player game. It doesn't matter if I am standing still or running, or if I am in peaceful or normal. I have already changed all of my video settings to the lowest they go. Also after I close the game I noticed my computer was still running slow. I checked my task manager and I found that the java from the game was still running and taking up most of my CPU. I did not have this problem with previous versions.

Steps to Reproduce:
1. open launcher. hit play (version 1.7.2)
2. open's new window. click single player. select world. load world.
3. blocks load slow or not at all. walking happens in jumps or not at all.
4. Check task manager. javaw.exe*32 see that CPU is at 100%
5. End and close game.
6. Computer still runs slow. Check task manager
7. javaw.exe *32 is still open and using 50% or more of CPU
8. end process. CPU returns to normal.