Hi Timothy
The only items that I am aware of that might fit this
list of criteria are
kwin, a handful of kcontrol modules, and possibly some smaller KDE
applications such as Okular. kwin is my current focus, and so far seems
to work very well without increasing the memory or CPU footprint. kwin
also satisfies Point #2 above by presenting a much smoother action in high
resolution TDE sessions when compared with twin due to its integrated
compositing engine.
But kwin has much trouble with multi screen systems. It can't scale images
across two or more monitors and has a bugs in calculating the window size -
i.e. minimize and maximize a windows shows holes in the window borders.
Hope, that multi screen will be tested exentsive than the bugs in KDE4 in this
area stops me using it.
Fine regards
Rolf