I've suspected this was the case but never quantified it, so very cool.
A couple of things I've found work very well are:
1) not creating deep view hierarchies in your table cells - ie. keep those very flat.'
2) Make your images as small as possible in terms of file size. Do background processing to make them smaller and lower the quality if you don't need it. This is by far the easiest way to increase speed if you aren't doing it already.
While its great to have a small image that doesn't require much I/O to read, "small" shouldn't only refer to file size.
Instead, a "small" image should be one that has a small resolution, and is stretchable. This lets the GPU tile the portions of the image that are being stretched and reuse GPU memory, instead of having to waste space in ram to hold duplicate pixel data.
(And when something's as small as it can be, it doesn't minify very well anymore -- not much left to strip from the PNG.)
I was referring to actual images used or featured in the table cell, not tiled backgrounds via UIColor colorWithPatternImage like you mentioning. But yes, it is important to do that as well.
A couple of things I've found work very well are:
1) not creating deep view hierarchies in your table cells - ie. keep those very flat.'
2) Make your images as small as possible in terms of file size. Do background processing to make them smaller and lower the quality if you don't need it. This is by far the easiest way to increase speed if you aren't doing it already.