What frame rate are you getting? If it's bang-smack-on something like 70, 72, 75, 85 or 100 then it may well be v-sync. Check what refresh rate your monitor is set to for your chosen mode. If this is the case then you can probably disable the v-sync somehow with your TDirectDraw (don't know, since I've not used it, but it'll probably be a property or a param to its Flip-like function) and have your program not wait at all.