Optimal pixel format for drawing on iPhone?

Pretty simple question: when doing some pretty intense drawing with CoreGraphics on the iPhone, how can I specify the pixel format to get optimal performance? Is the format that I get from the context via UIGraphicsGetCurrentContext per definition the best one? I know that RGB565 is supp开发者_开发问答osed to be the fastest to use in OpenGL. Does that go for CoreGraphics as well? General advice?

k32BGRAPixelFormat and k16LE565PixelFormat (and their CoreGraphics equivalents) can be counted to be hardware accelerated on all iPhone/iPod touch models.