My FPS has been dropping suddenly around 100 frames or more during quickplay and 1 competitive match (I also got disconnected and lost SR as a result and didn’t try comp again after) since the summer games update to the point where the game is nearly unplayable. I tried all the solutions suggested on the forum for FPS drops/lag like repairing and changing to low settings and even reset my laptop (running GTX 1070 and Intel i7-7700HQ CPU) to factory settings, completely wiping it and reinstalling the game but still having the same issues. I tried running witcher 3 at max settings to test if there were similar FPS drops but nothing noticeable occurred, which leads me to believe that the problem is just with Overwatch.
Is your Windows up to date, and also are your graphics drivers up to date? If yes and you did try all the troubleshooting steps, please provide a dxdiag for your computer. Instructions here: Blizzard Support - Obtaining System Files
Please be advised, this is an OS issue. The problem is coming directly from Microsoft. Multiple friends of mine are having issues with their nvidia 1080 and frame drops to the exact same range. Please fix this immediately as it is absolutely unacceptable and makes the game unplayable or at least yell at Microsoft to do it!