On my system this problem shows up when I enable fractional-scaling (which I have to, to be able to use different scaling for my notebook's 3k display and my external monitor).
As soon as I close my notebook's lid or disable fractional-scaling, performance on the external monitor is back to normal.
On my system this problem shows up when I enable fractional-scaling (which I have to, to be able to use different scaling for my notebook's 3k display and my external monitor).
As soon as I close my notebook's lid or disable fractional-scaling, performance on the external monitor is back to normal.