performance optimization / Alpha Toast

Hi there,
I'm working on a patch based on the Alpha Toast patch by Andrew Benson and I'm having problems with the fps rate.
I would like to understand if there's a way to optimize the performance or if what I'm trying to do is simply too heavy for the CPU.

I'm basically using the Alpha Toast twice to add a masked layer to the original patch and then I'm processing one of the masked vids. Everything is 640x480 and I get around 10 fps. I have the sensation I'm doing something wrong but can't say what. Maybe 640x480 is simply too much ?

Hopefully from the img will help to understand what I'm doing..

thanks !
g.