Comment # 10 on bug 941931 from Michael Chang

Looks to me that the video ram is too small to enable page flipping by swapping
poiners of on-screen and off-screen buffers in video memory to update the
screen quicky [1]. 

Some relevant log outputs

VBE info:
  total memory: 16384 KB

* 0x1d4 2560 x 1440 x 32 (10240) Direct Color, mask: 8/8/8/0 pos: 16/8/0/0

page_size = pitch * height = 10240 * 1440  = 14745600 = 14745.6 KiB
vram = 16384 KB < 2 * page_size = 2 * 14745.6 KiB = 29491.2 KiB

Without page flipping, the screen update would be way much slower by
bit-blitting from system memory to video memory and no longer a simple pointer
switch.

[1]
http://git.savannah.gnu.org/cgit/grub.git/tree/grub-core/video/i386/pc/vbe.c#n1114