I use Handbrake and AnyDVD to rip DVDs I buy to iPhone/iPod Touch format so that I can watch them on flights. Since I fly quite often (to the DevExpress offices in Glendale, various conferences, home in England, etc), watching what I want to watch during these boring flights has been a life-saver, or at least a sanity saver.
I recently updated to the latest Handbrake, version 0.9.4. Nicer GUI, more intuitive selection of options, a zillion fixes, seemed like a winner. Just now I started to rip the zeroth episode of Doctor Who series 4 (The Voyage of the Damned). It's a 72-minute episode and it damn well took nearly 72 minutes to encode. WTF? Encoding speed was about 30 frames per second and during the entire time the CPU meter didn't go above 30%. In essence, it was not using all four cores I have on this desktop, which frankly is a waste of time and resources. I checked the options and it certainly should have used them all.
So, I uninstalled it and reinstalled 0.9.2 -- the previous version I'd been using -- and started on the next DVD for episodes 1 to 3. The CPU meter is resolutely nailed to 100% and the encoding speed is around 100 fps. Much more like it, however I'm flummoxed to understand why the later version isn't as fast or, rather, why it's not using multiple cores. Oh well, can't be bothered to investigate, I just want to be able to get the job done quickly.