Hi, JUCE talent team.
I sent a PullRequest to your GitHub with the following content:
I found a code that is a performance bottleneck when running on Retina Display with CoreGraphicsRenderer.
Actually, since NSHighResolutionCapable is set to true in Info.plist on Retina compatible applications, CoreGraphics seems to automatically scale internal back buffers by scale factor (factor is x2).
However, as I have seen, I recognize that there is a problem that JUCE side is doing affine transformation (scale multiplication).
I think that this implementation is the cause of the following problems that have been posted by JUCE Forum.
Drawing images on MBP Retina is ultra-slow
On the other hand, when using SoftwareRenderer, the above scaling processing is necessary.
Based on the above, I propose an implementation that does not change displayScale value
when using CoreGraphicsRenderer.
This Pull Request dramatically improves graphics performance on retina displays, which has long been an issue.
When this Pull Request is merged, it leads to solving the problem in my project.