Poor performance when one display is rotated/inverted

Hi,

I have 2 different monitors (one LG 24’’ 4k 60hz and one AOC 24’’ QHD 144hz) both connected to the same GPU (RTX 2070 Super) via DP cables.

Because they have different heights for VESA mounts I use the LG upside-down so they can be aligned.

Whatever display manager I use (tried GNOME, KDE, XFCE), whatever display server (tried xorg and wayland) or distro (tried multiple ones) both monitors work pretty well until the point I setup my LG display as inverted (rotated 180°).

After rotating the display the output performance on it becomes extremally poor to the point that it becomes unusable, the mouse moves slowly, the windows becomes laggy, it’s like if after rotating the monitor starts to output the image in 5-7 fps. And it only happens in the rotated monitor and only if rotated, the image on the other monitor works as usual and as soon as you disable the rotation the display starts to work as normal again in the LG one.

I’m almost convinced this is a Linux specific Nvidia Driver issue as on Windows 10 rotating the display just works as well as with an old AMD card on Linux there is no problem too.

Does anyone have any similar setup and issues or can instruct me how to fix it? Also, googling similar situations it looks like this has been reported multiple times in multiple different scenarios since years and years ago.

Thanks for any help in advance.