A couple of things you could try:
Bring up Task Manager in Task View and click View / Select Columns ... and then add other columns that might be bottlenecking FMS such as Paging, Memory or I/O. When you find what's the problem then look to see if any other tasks are hitting the same bottleneck. Stop them and see if that fixes it. Also try varying the FMS display modes to see if that affects things.
Similarly Run MSCONFIG and temporarily disable the non-Microsoft items in the Start list. If that fixes the problem then re-enable them one by one to see which is causing the problem.
Another way of doing much the same thing is to download GameBoster from IOBit: free,
http://iobit.comHope this helps. John