That was exactly the reason. I think I have made a nice c-program that will monitor cpu load over test-runs. All I need to do now is to get it all lined up, run it and write it up. That will take a week or two though, I'm pretty busy at the moment.
But the informal test of just watching transcoded stuff on my tv, ipad and so on shows that my cpu can handle it. No stutter, no lags, no delays and so on. But my main movie collection is almost exclusively mkv with h.264 so the transcoding is limited. I will do more thorough tests though.