440 drivers super choppy & kill video memory, 1080Ti

Full bugreport here, & related ubuntu software & updates bug here, in short:

Xubuntu 20.04, but was the same in 19.10. nvidia-drivers-440 make streaming video laggy/choppy and mean lag is noticeable elsewhere, suggesting video memory is highly depleted. Moving the cursor with keyboard arrows in my coding program showed serious lag until I switched a setting. Easiest way to replicate is just fire up zoom and wave my hand, which shows huge lag. Trying to type while zoom is open (e.g. take minutes) is nightmarish.

Works fine with the open drivers. Before I go down the path of following the proper bug report log file approach, does anyone on the team know if this is a known issue? I looked for “choppy” and “laggy” and “lag” but there are tons of results and none of them looked related enough. I’m aware that the 450 drivers have just pushed and so will feasibly be reaching the official updates repository at some point (any idea when? I see they’re in 20.10 repository but won’t make it to 20.04?), so if this is about to solve itself there’s nothing I need to do.

Equally if the updated drivers are not going to help then I’ll go get the required log files.