it depends on a few factors, obviously.

do the regions you are trying to swap have the same aspect ratio?
how beefy is your machine?
how fast is your memory?
how high is the screen resolution?

also, try bringing up the maxfpsbk (it would seem to improve the first frame displayed when it's higher)

as an fyi... my 5x box will pip swap within a second. i'm running 50/50 fps @ 1920x1200 on a quad core and an nvidia 260

let me know if that helps