What is your computers specs? What version of toast?
The more CPU speed you got, the faster it can go. And RAM doesnt hurt either.
Ill say it again, video encoding is one of the more CPU intensive things you can have a computer do. Minimum 24 frames per second, and each has to be encoded. Is it going from PAL to NTSC, more time. Avi to MPEG2, more time.
Basically, know what you are trying to get out of encoding, and understand the amount of processing involved.
A 5min avi will take no time to encode into MPEG2 for a dvd, but the same avi will take much longer if you are encoding it from HD (larger frame footage), different frame rates etc etc.
Give it time, or buy the best computer you can.