There are several issues with the way we handle drawing of images in NGRegion (do we handle fractional insets correctly? We don't handle retina correctly. And this). One of these is that we have a check in the region cache steps where if the width or height is fractional, we skip the cached image and go straight to drawing all the paths. This kills performance not just on iOS or Pi, but also on Desktop when this case is encountered.

The quick fix is to remove this check, and then compensate in the 3 or 9 patch rendering code for the case where the width and/or height is too small for the insets provided.

A subsequent pass should happen over all this code to fix the other issues such as Retina.