How hard is it to display a colored rectangle in OpenGL ES?

For example I want to display a rectangle like a UIView and assign it a background color. Then I want to update the color and size of the rectangle. Is this hard to do开发者_JAVA百科? How?

Note: I need dozens of these rectangles and have to update them as often per second as possible. The performance of Quartz / UIKit / CA isn't good enough for my case.

OpenGL would be overkill for such a trivial task. Quartz and CoreGraphics is more than cable of doing this. Check out the Drawing and Printing Guide for iOS