So what's the autopsy report on the Nintendo DSi? Why is the battery life notably worse than the DS Lite? Over at bunnie: studios, the eponymous Bunnie ripped one apart, and it looks like we have our answer: a beefier CPU to handle the video and audio stuff.
I haven’t had much of a chance to play around with the device yet, but from what I can tell the CPU is substantially beefed up (consistent with reports of the DSi battery life being shorter than the DS-lite, despite having similar battery capacities of 840 mAh for the DSi and 850 mAh for the DS-lite), as it can do all kinds of real-time image manipulation tricks on the video feeds, and it also has a built-in minigame for audio streams where you can loop in samples over music files and do some low-quality pitch distortion on the fly. The markings on the CPU package yield no clues about its performance, but my guess is that any ARM9 or ARM11 CPU manufactured in 2007 would have a performance around the 266-533 MHz range.
Inside the Nintendo DSi [Bunnie Studios]