Sakurai says that the reason the Circle Pad Pro wasn't supported was because of Processing Power Limitations

[Jizz_Beard_thePirate]

Well... To be fair... When playing SSB for 3ds, you can't access the miiverse or the web browser while runnning the game, and those do require additional resources to run so I do indeed believe him when he is saying that cause to me, it seems running SSB3ds at 60fps even in 3d mode requires a shit ton of horsepower that the 3ds can bearly manage! So, even though its 5%, I think SSB is pushing the 3ds to its absolute limits so even that 5% counts