Well you could get a new fast computer, but in place in that there's a few things you could try. I don't think a single one of these suggestions will make a big difference but doing everything you can should cut some time off encoding. First you want the source data optimized. Defrag the disk the movies are on to ensure that the file in is one big chunk and is quicker to read. Next, you want the drive your movies are on to be as fast as possible. If you have multiple drives you can test for the fastest one.

Now the connection between the source (video) and the destination, the CD. It would be ideal if your hard drive and burner were on the same bus (ATA, SCSI, FireWire, etc.). That way the data doesn't have to jump too far and get slowed down. Also, internal buses are generally faster than external buses so it would help if the source and target are physically inside your computer.

The burner application may have buffer settings to increase to give a fuller supply of encoded data. Through software you can give Toast more memory, quit other applications and trim active extensions.