MacRumors had previously reported that the new NVIDIA-based MacBooks and MacBook Pros showed dramatically less CPU usage when playing back H.264 content. The conclusion was that Apple had enabled the use of hardware acceleration for H.264 video playback. H.264 is the video format that Apple encodes all iTunes video content and movie trailers in, so any improvements in playback would benefit a large segment of customers.
Click to enlarge, Left: 1st Gen, Right: 2nd Gen
Based on early testing, it appears that the 2nd generation MacBook Air also delivers performance improvements during playback of H.264 video. One important additional advantage, however, is that this also appears to dramatically decrease heat production in the thin laptop. One of the early complaints about the original MacBook Air was related to overheating during video playback.
Forum member NC MacGuy performed side-by-side H.264 playback testing of a 1st generation 1.6GHz MacBook Air and a 2nd generation 1.86GHz MacBook Air and found a 10 degree difference in temperature between the two models. The lower temperature reflects the fact that the 2nd generation MacBook Air's processor was running at a lower clock speed (800Mhz) than that of the 1st generation (1.4GHz). The new MacBook Air was presumably able to further throttle the CPU speed down since the GPU was now handling much of the H.264 playback.
