MTM has the feature that you can use Expression Media Encoder 4 to record the test run as a video. To enable this feature, after you install MTM, you have to install the basic version of Expression Encoder, and a few patches see notes here for a list of files and the process.
I recently did this on PC and tried to record a video. As soon as the recording process started the PC virtually stopped. It ran to 50%+ load on a dual core 2.3GHz CPU and the mouse disappeared. As soon as I stopped MTM (via task manager and the keyboard alone) it became responsive again. If I ran MTM without a video recording it was fine. Should be noted that if I ran the Expression Encoder (not via MTM) I got the same problem.
Turns out the problem was not the PC performance but the nVidia video drivers. Once I updated these to the current ones from the nVidia site it all worked as expected.