As long as you are not using your Virtual Machine to test sketchy or otherwise suspicious programs, you may wish to disable your Antivirus for increasing your Virtual Machine performance. You can add VM folders in your antivirus exception list. To do so, follow the below simple steps: In Host OS open Avast Antivirus. Click on Menu and a new window will appear. Click on Settings and a new window will appear. Go to Exceptions and click on ADD EXCEPTION button and a new window will appear. Either paste your Virtual Machine folder path or click on BROWSE and select your Virtual Machine folder and click OK . All done, now Avast will not scan the files from provided path. Caution: Please do this at your own risk. A virus from the Host Machine can infect the Virtual Machine and vise versa.