Alpha channel is making my video drop frames ,or move very slow.

    Mar 30 2010 | 10:10 pm
    I have a pdf that is black and white that I am putting in top of a video passing it through an alpha channel to take the white away from the pdf. the main problem is that this process makes my video run extra slow, i tried the colormode uyvy , videoplane amongst other things and none seem to work...
    here is the patch.
    thanks in advance