Fullscreen is faster?

[retrotails]

I've googled this and found no similar results, sorry if this has come up before.
When I run any game, it will run much faster in full screen. I've tested many GameCube and Wii games.
This is true for games that run really slow (Metal Arms: Glitch in the System) and really fast (Castlevania: The Adventure ReBirth)
In NSMB Wii for example I get a relatively consistent 30 FPS windowed, and a solid 60 full screen. I ran these tests at native resolution, but if I go from native to 3x native it still runs the same, 30 FPS windowed, 60 FPS full screen.
My first thought was that it might have frame skipping on, but I know 60 FPS when I see it, plus if I set the frame skipping to 1 in windowed, it's noticeably choppier (still like 28 FPS, really not 'choppy' just 'not that smooth') and still not quite full speed (~55 VPS)
My second thought was the frame limiter, but that isn't it either (as a side note the tested area on the map screen got 80 FPS in full screen without the limiter)
Just out of curiosity, I tested the fastest running thing I could demo, Castlevania: The Adventure ReBirth. The menu got 260 FPS windowed, 610 FPS full screen.
Windowed mode is the default size, full screen is my monitors' native 1920x1080.

Ubuntu 12.10 x64 with Xfce
Dolphin 3.0-845 (It's been this way for at least a few weeks)
i7 870 without hyperthreading @ 2.93 GHz (Dolphin says 2 threads per core still, for some reason)
8 GB DDR3 (unknown clock/manufacturer)
Radeon HD 5770 w/proprietary drivers, unknown version

[23732]

I think that is because the GPU doesn't have to render the desktop and Dolphin at the same time

[retrotails]

I think that is because the GPU doesn't have to render the desktop and Dolphin at the same time

Then why is 3x native the same speed as native? Obviously the GPU has no issues keeping up.

[DefenderX]

No. The reason is simple: Your GPU is strong enough to handle 3x IR

[Zee530]

I think that is because the GPU doesn't have to render the desktop and Dolphin at the same time

No, i'm pretty sure the GPU is rendering the desktop even if it isnt shown, this most likely has to do with downscaling or his full screen resolution is different from the windowed resoulution, try setting the fullscreen resolution to the maximum.

[neobrain]

Rendering the Desktop has zero influence on the emulation performance. The Desktop only gets redrawn when it actually changes (not sure if that's the case in aero, but even then the performance impact is ridiculously small).

EDIT: Oh and he's not even using Windows, go figure. I.e. the behavior of the Desktop likely is the same for fullscreen and windowed mode.