At half gas CF,, Steel and Al are all pretty rigid. The bottom bracket stays pretty still and most of the power from your pedals goes into the drive train and this power goes into the rubber hitting the road. As you crank up to full gas the bottom of the frames start to flex from side to side. This lateral movement absorbs power. Pedalling in circles rather than squares helps reduce this swing but CFs greater rigidity reduces the power bleeding into the frame more than the others.
We are talking power levels on the cranks by legs that cruise above 25 mph for hours on end for fun. In other words if you go 25 miles under 50 minutes these properties are important - for the rest of us they amount to next to nothing.