I believe we’re running into a similar (showstopper) issue as well with horrible performance on Windows since switching to JUCE 8.
Switching to the software renderer does not seem to be solving the issues when dealing with ImageFileFormat or other use cases of images created from memory or disk.
In general I have to say that it’s an extremely painful breaking change and having a common type like Image be intertwined so heavily with a specific renderer (by default!) seems wrong to me.
I think that instead - the Direct2D uses of Image should be explicit and not implicit.
I’m now waiting on a new Windows machine that would hopefully help me debug and profile this issue more clearly, currently we’ve just had all test machines show a severe performance regression.