I'm pretty sure there is some serious memory issues going on with TPM 2012.
The game will begin stuttering after about 30 minutes (give or take a few). If I don't restart it, the program will eventually start stuttering so bad as to be unplayable and requiring a hard-close through windows.
I've checked the memory usage of the game and it gets surprisingly high for it's size. My last stutter-out showed the program using 1.3GB of RAM. Considering the whole game install is much smaller than that, it's looking like there are some nasty memory leaks happening. The 1.3GB usage hasn't been a problem on my system in the past (larger RAM usage than that has been fine) but it seemed to be in addition to the game's stuttering which made the RAM usage fluctuate a good deal, too.
Specs:
Win7 64-bit Home Prem
PhenomII X4 945 3Ghz
4GB RAM
AMD HD5770 video card w/ 1GB vid RAM (driver date 6/11/2012)