I tried it out. I even made a horrible youtube video (which I may or may not post) showing it. The Wii U took almost the exact same amount of time getting from the off position to the actual game when compared to the Xbox 360. I even took things a bit further--from the title screen to the actual game starting, the Wii U got me online and in a team death match FASTER!
How could this be, you ask? Well, the Wii U goes from the Wii U intro to log in to choosing a game faster than the Xbox goes from 360 intro to log in to choosing game. The 360 wastes valuable seconds. Meanwhile, the Wii U is on a static load screen. The load screen was where the 360 caught up. Depending on which console I press "power" first, the winner comes down to about one second. I tried it multiple times.
So, the Wii U may not be as slow as we make it out to be (though going from game to the title does take a long time and I suspect many apps like Netflix will be a toss up, as well). The 360 just hides it better. I didn't toss the PS3 into the equation since, from my experience, the 360 has always been the faster of the two.
