--- Comment #10 from Michael Chang email@example.com --- 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 .
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.