You really are onto something with this. I also noticed that my MBP 16 stops lagging as hell and starts being a proper expensive productivity laptop when I have Youtube in the background while keeping on the Intel gpu. As soon as I let Intel gpu "go idle" and start typing, the lag is back... In a similar boat here.. MBP 16, tried all the resettings and etc. Even erased the disk and reinstalled the OS, none seemed to work, obviously Apple Support didn't really help either, they suggested erasing the disk without restoring from a backup, not really sure if that's gonna be entirely worthwhile because I do get the feeling that this has got something to do with the graphic card.. Has anyone tried their luck at an Apple Store?

ANy news on lagging slow BIG SUR? I have the 11.2.2 update and still lagging ... embarrassing no? Updated to 11.2.3 only just now, the issue seems to have disappeared. Will give it a few more hours/days and see how it goes. But as the above users commented.. I do get the feeling that this has got something to do with the GPU. Occasionally when I open an Adobe app the screen will turn half black with weird marks. Will report back either way.

After the .3 update the issue is still here unfortunately, I would say it's better, for whatever reasons, but still here. Noticeably when switching tabs in a browser, the black screen of death would pop up when I start or close Adobe software like Photoshop etc.. Given up literally, would just take it to the Store.

This happens when an external is connected to the macbook Thanks for your reply, but what did you mean by an external? I don't use any monitors, the things connected are an external hardrive and a USB dongle.. Do you reckon those might be the cause?

This is f***ing ridiculous. 🤯

The issue is still here apparently, after the 11.4 update.

Since I've started using an external audio interface I had faced the same issue. Apple, please, fix it! *Patiently waiting for more shitshow with the upcoming macos..