Comment # 13 on bug 941931 from Jan Matejek

so, some measurements. taken with a stopwatch in my phone so sub-second
precision is going to be wobbly
timed from the moment when "Loading GRUB" in 80x25 textmode flashes on the
screen and immediately disappears


at 1920x1440x32 (does not fit double-buffer, rendering is visible)

themed GRUB takes 4s to render the screen, and 1s to switch between items
(i forgot to take note what happens when an item is selected; it's probably not
significant, perhaps it disappears immediately)

gfxterm GRUB with no background takes a little less, maybe 3-3.5s to render the
screen. switching between items is immediate
after selecting an item, takes another 3s to "de-render" the screen, clearing
it line by line, before boot starts


at 1600x1200x32 (fits double-buffer, screen displays at once)

themed GRUB takes about 3.5s to render, around 0.7s to switch between items
(again, not sure what happens after selecting item)

gfxterm GRUB with no background takes a little over 2s to display
after that, additional 2s before it starts responding to keyboard input
switching between items is immediate, booting is also immediate

the additional delay *seems* to correspond to clearing the second buffer in
advance?


presence of background image doesn't seem to have an effect when
double-buffering; i didn't take measurements with it, but it didn't feel that
removing the background image made it faster.
when not double-buffering, the background image takes its own time to render,
but doesn't "de-render" like the gfxterm border and instead stays on the screen
as if in background layer, presumably until the kernel takes over