Oops, OK I guess there are no special options left.
Only the behavior of the “XRender setting” of Kwin is better (at least on my system)
I tested the settings with the combinations of direct/indirect rendering with vsync on and off (kwin opengl):
In comparison to Xrender all of these are definite slower on window drawing @ resizing and the "initial appearing" on the screen when opening a application.
To remind (you have to watch carefully an no fading or such things): There are visible
drawing events in the sense that not all elements appear at the same time.
If it would be a only Qt related problem, then:
1) why not with compiz (except in this case the resize is also laggy)?
2) why also on gtk apps with metacity or gtk apps with kwin?
3) why there are not such problems on an almost identically configured system with an
i915 in combination with a much slower CPU?
(Despite there are other problems for i915 there, due to the outdated chip. But resize is faster, also all elements of a window appear like a flash.)
So I guess it would not be fair to claim it only a Qt-Problem!!?!
(Despite gnome on cairo is definitely snappier on drawing than kde 4.3 on Qt. And Qt should care about the much more advanced fontrendering on cairo ...but that's a other topic...
I will keep on hoping for 2d bugfixing by nvidia anyway. First the basics than the more hype things!