Hesitations since installing window 7 64 bit

Dell t7500 windows 7 64 bit 16gig of RAM. System OS crash required a reload of the system. Since the reload and reinstallation of all the ms updates the system continually pauses to update text, and mouse movements. Also the sound seems to have taken a turn for the worse. Diagnostics run good with no problems, Windows does not seems to have any hardware problems with drivers installed.

Looks for a little diagnostics help in removing the problem.