How do you export the recording to your Mac without using 150% of CPU?
With "export" you really mean exporting, don't you?
When I use ScreenFlow and after the recording is done and export it to one of many formats (most often .mov using the Apple Intermediate Codec), the CPU spikes too, since exporting is a CPU intensive tasks.
But if you mean recording, then ScreenFlow uses much less resources during recording than QT X does, that is why I prefer ScreenFlow.
As far as I know, all screen recorders use a highly compressive codec to store recorded footage in.
Or am I just misunderstanding you?
Btw, your thread is tagged as resolved, I don't know, if that is true, since you still seem to be looking.