First up on a Retina display you’re using bi-linear or bi-cubic scaling (I forget which one exactly).
Recommendations:
- use window.bitmapforcaching to get a pixel perfect image on the first line.
- graphics.antialias = false, draw picture, re-enable.
- Use CoreGraphics declares to disable the high quality scaling of images.
We talked about improvements with images on this thread Efficient Canvas Drawing