Hi,

With an ultrawide monitor (21:9 1440p) grub has trouble to draw the
screen, flickers when pressing a key and has a really high imput lag.

When booting, the grub menu at first badly drawn (with parts that looks
no initialized) and then the menu become finally readable.

After that pressing the keys has a an high input lag and when changing
"screen" (from the menu to the cmdline for example) the new screen is
badly drawn again for a few seconds.

The videoinfo command is giving me the correct resolution:
0x1d4 3440x1440x32 (13824)

The bios itself doesn't seem to be displayed at the native resolution of
the screen but is not showing any problem. The early boot of linux (with
plymouth) is then using the native resolution flawlessly.

Kind regards,

Laurent Bigonville