I’m still buffering to image on D2D in some cases. I have realtime visualizations drawn over seldom changing backgrounds where both are paths with a node per pixel. If I don’t buffer the backgrounds, their constant redrawing slows things down. The paths are not created in paint(), they’re stored, but I don’t know if D2D is caching them, which may make a difference. One optimization I removed was reducing the repaint area to the actually changing part -this made a big difference on the software renderer, but seems to be irrelevant on D2D.
Anyway, after some testing this issue has nothing to do with D2D. ClearType needs to render over the actual background, which is not possible if the component is transparent and rendered to image. So with ClearType enabled, a transparent component with text can’t be buffered.