We are sorry to hear that the PVS has been slow for you at times. Usually slowness in the PVS is due to processing power available on your system. The more processing power available the faster the PVS will work.
If you refer to the PVS quickstart guide in the course you are taking, usually in the "Download the Exercise System" lesson, it will provide some guidance on ways to improve the experience. For example, if your system has the minimum required RAM and CPU, you may need to make sure no other programs are running at the same time (no outlook, no MSWord, etc).