drawAtPoint: and drawInRect: both call through to drawInRect:blendMode:alpha: which calls through to CGContextDrawImage. CGContextDrawImage has some optimizations to handle unscaled blends and further optimizations for unscaled blits, but it doesn't use the GPU on iOS. Even if it did, it would be using the GPU to draw into a temporary buffer that would have to be drawn again when the QuartzCore scene is rendered.