Handbrake is an open source video encoding application for Mac OS X that is easy to use and turns your regular DVDs into high quality H.264 MP4 files compatible with VLC and Quicktime.

I get 22 frames per second on a 2.16GHz MacBook Pro with 2 gigs of RAM using high quality settings and 2 pass encoding. Your speed comes down to the speed of your hard disk in most cases. There are 3 ways of doing your encodings and here are my results with each approach:
1) Rip straight from the DVD disc and encode to H.264 on the fly.
Avg Speed: 18 FPS
2) Rip to main hard drive using MacTheRipper, then encode with source and destination files on the same drive
Avg Speed: 22 FPS
3) Rip to main hard drive using MacTheRipper, then encode, making destination an external firewire 400 drive
Avg Speed: 30 FPS

Whilst the differences in speed are only a few frames per second, you can see that the third way is almost 2x faster than method 1. So if it takes you 4 hours to encode a movie, those few frames add up over time making a big difference to the time it takes to complete, almost halving the time you would normally have to wait.

The first way is obviously going to be the slowest, as the processor has to decode the DVD CSS and encode the H.264 at the same time. The second approach of ripping to the hard disk first and then encoding afterwards would seem to be much faster, but on a computer with dual cores there isn’t much difference. Surprisingly the third technique was the fastest, the reason being because if the destination and source are on the same hard disk, the hard drive’s read head has to constantly switch between reading and writing almost simultaneously, therefore making the drive thrash around seriously degrading performance. Using 2 drives means one can just concentrate on reading, whilst the other can just worry about writing to disk.

The machine I am using only has a 4200 RPM drive. Using a much faster 7200 RPM drive would probably give much faster performance so if you have two fast hard disks in a machine, use them. H.264 encoding does takes a lot of power and time to complete, so you are probably best to leave your rips running overnight.

If you are interested in encoding movies for your iPod, you should try Instant Handbrake, which is available here.