If you *really* don't want to put too much CPU into these screens, you can always just pre-render your stuff offline.
E.g. you can render lots of source code into a small texture ( e.g. using a 3x4 sized font, you can fit 256x256 characters into an 1024x1024 texture ), and the same with hexdumps. You can write a smaller piece of code rendering some randomgenerated mesh and highlighting some vertices on it, adding a few bits of random text at the left side ( just make the line-lengths feel natural, it looks weird when there's too much difference in linelengths ), make your animation loopable and then pre-render it into images. I'd suggest low framerates.
Voi'la, you now have lots of screens rendering simple textures. Heavier on memory, lighter on CPU. Of course, you can use hybrid approaches too.