On the Apple developer web site you can watch the WWDC videos, there is one on graphics and animation that talks about just that. Conventional wisdom, especial

On the Apple developer web site you can watch the WWDC videos, there is one on graphics and animation that talks about just that. Conventional wisdom, especially for small images, it is much more efficient to draw them with Core Graphics than use a image, more so if there is transparency in the image. This will even be true for non-ios systems. Microsoft has said for years, that generating a 16x16 image is faster than getting it from disk (depending on complexity and disk speeds). Plus, code does tend to be more compact (again, within reason), so it is less that has to be loaded when your application starts.