<p>I asked before about pixel-pushing, and have now managed to get far enough to get noise to show up on the screen. Here's how I init:</p>

<pre><code>CGDataProviderRef provider;
bitmap = malloc(320*480*4);
provider = CGDataProviderCreateWithData(NULL, bitmap, 320*480*4, NULL);
CGColorSpaceRef colorSpaceRef;
colorSpaceRef = CGColorSpaceCreateDeviceRGB();
ir = CGImageCreate(
320,
480,
8,
32,
4 * 320,
colorSpaceRef,
kCGImageAlphaNoneSkipLast,
provider,
NULL,
NO,
kCGRenderingIntentDefault
);
</code></pre>

<p>Here's how I render each frame:</p>

<pre><code>for (int i=0; i&lt;320*480*4; i++) {
bitmap[i] = rand()%256;
}
CGRect rect = CGRectMake(0, 0, 320, 480);
CGContextDrawImage(context, rect, ir); 
</code></pre>

<p>Problem is this is awfully awfully slow, around 5fps. I think my path to publish the buffer must be wrong. Is it even possible to do full-screen pixel-based graphics that I could update at 30fps, without using the 3D chip?</p>

I suspect doing 614400 (
```
320*480*4
```
) memory writes, random number generation and making a new object each frame is slowing you down.
Have you tried just writing a static bitmap to screen and seeing how fast that is? Have you perhaps tried profiling the code? Do you also need to make a new CGRect each time?
If you just want to give the effect of randomness, there is probably no need to regenerate the entire bitmap each time.