ok, i tried some different things using the scientific approach
i tried the same situations on my computer with:
1 - 1920x1080, all high, fullscreen
2 - 1920x1080, all high, windowed
3 - 1280x720, all high, fullscreen
4 - 1280x720, all high, windowed
i tried 3 different things on all these resolutions
a - spinning around 20 times in one place
b - straight walk 10 paces
c - time it takes for the hall of fires first button to shut the first trap door
Did everything three times using stopwatch (rough median results)
1a 29 sec
2a 28 sec (!)
3a 22 sec
4a 20 sec (!)
ok, nothing special, full screen mode is somewhat 'slower', high res is slower, move on.
1b 6,5sec
2b 6,0sec (!)
3b 5,0sec
4b 4,5sec (!)
ok, not much difference here, move on
1c 6,0sec
2c 6,0sec
3c 4,5sec
4c 4,5sec
... times here were identical.
!!!
so i would guess 'the heartbeat' lasts longer if using 1080 then 720, but you can do the same amount of moves in that time. the difference is that when using fullscreen vs. windowed mode there seems to be something like a 10% decrease in the actions per heartbeat department.
dont know whose 'fault' it is, maybe a directx issue when switching to fullscreen? card driver issue? maybe i am way off and my stopwatch needs mending, maybe am just biased because i finally made that level with a windowed view...
anyways, hope this could potentially help someone.