Something just don't add. It's a framebuffer (edram) limitation? a wireless bandwidth limitation? I don't think it has anything to do with compute power, because it would depend on what's happening on each screen, and not on the number of screens.

These things are bound to happen. It would be noticed more on the Wii because of the honestly, shitty hardware.

Wii U looks like it's gonna be one hell of a machine, so if Mario Kart U is/will be running at 60fps, then I can't see i dropping too far below 30fps, even with 4 players. You have to keep in mind too, that not every multiplayer game will require, or even use 2 gamepads. 

It will be a rare occurence for a few games. Nothing to scream and shout about.

Did the MKWii framerate drop below 30fps in 3+ local MP? I thought morenoingrato was talking about the more simplistic environment in that case (Nintendo took stuff out so the tracks looked simpler to avoid poor framerate)

As mentioned though this doesn't seem like a graphic processing problem, but something else... perhaps it is a wireless bandwidth issue (which means it will only affect the frame rate of the controller screen... normal TV framerate will as usual be dependent on the developer... ie it will likely also be 30fps, but not for any fault in the hardware)

This isn't a big deal, 30fps is the standard for most HD games, and many of the smoothest games still have framerate hiccups here and there.

And don't forget, it's not like both screens are going to be displaying the full game simultaneously along with the main TV screen. 99% of the time they'll just be displaying arbitrary menus and HUD stuff when playing games using the TV as the main screen... and if you're playing a full game on the Wii U screen instead of the TV, then obviously you're not using a second controller so the point becomes moot.

Well we don't know enough about it yet, you may be able to play 2 player games using the pads instead of the TV.

They'd most likely be relatively simple games like the "Othello" game shown in last year's E3 demo for example, or certain 2D games like NSMBU.  I highly doubt we'll be able to play games like Call of Duty exclusively on the small screen when using two tablet gamepads simultaneously, but if that somehow turns out to be true, it would then become a HUGE selling point of the system.

It did drop from 60 fps to 30fps in 3 player and 4 player local mode.

This threads is omitting basic logic.

There is a limited pool of resources for any given system. You can't take 5 cookies and give 3 people 5 cookies.

Your processing the data an additional time for each screen added. Either the frame rate gets lowered or the game will have to use less of the systems resources keep at 60 FPS.

which might suggest that most games won't support 2 pads.

Not necessarily. Sounds to me like this is more to do with a bandwidth limit in the wireless communications than a processing limit in the Wii U itself. Otherwise, running a low-requirement game on two tablets wouldn't hit the framerate at all, right?