Make sure your computer meets the Diablo III System Requirements.
The game requires up-to-date drivers to run smoothly. Update your drivers regularly.
Run the game in Administrator Mode to address any installation errors.
Make sure your game is fully up to date by opening the launcher and allowing all downloads/updates to apply. Press Play when you see "Game is up to date."
Run the repair tool to resolve issues with damaged game files.
Many overlay programs can create instabilities in the games they're trying to enhance. A list of overlay programs that may be problematic with Diablo III can be found on our Diablo III Software Incompatibilities page. If you have an overlay program that does not appear on this list, it could potentially cause an issue and should also be checked.