That's wrong. Exclusive fullscreen mode doesn't speed up rendering significantly, only a very little bit. I did the test with TUER under Microsoft Windows NT 2000 and there was no difference of performance, the same under Vista.
That depends.. In 6uX (where X < 10) on windows in full screen mode Direct3D may be used for
rendering (as opposed to DirectX, which is the default). It won't make much of a difference
if the D3D pipeline couldn't be enabled.
In 6u10 if the new D3D pipeline can be enabled at all it is enabled in both windowed
and full screen modes. If it is enabled, you may see some difference in fs mode
just because there are less restrictions on what can be done in FS.