I've done something similar for DBus deserialization. It turns out that I stumbled upon something called fixed-point optimization for loops (in DBus: arrays), similar to what the JVM does according to Cliff Click's very interesting talks. It was pretty fun to write basically a toy optimizer that is even useful. As a friend said, it's probably overdesigned, but it was fun and it does yield code with not much left to improve. Well, except for embarrassingly optimizable types such as arrays of fixed-length elements.
We will probably see more such things as the consequences of the end of the free performance lunch play out.
As a former Skia contrib, this is cool as heck to read. It's exactly the sort of optimization work we had in mind when we wrote that SkRecord system, and I'm pleased that you were able to make use of nanobench. Back in those days we had just a few small optimizations that we could apply, mostly trying to eliminate unnecessary saveLayer() calls. Very cool to see it done in a modern way with Lean.
I do something related in my gpu library. After a few frames if the push constants don't change I compile the shaders in the background with them defined out by the preprocessor to reduce the size of the shader program (kind of like a branch predictor). I also store the entire pipeline in a graph data structure that I partition into segments that let me fuse and split kernels (though I hadn't implemented those optimizations yet). In my mind one issue with these GPU accelerated programs is that there isnt a runtime with the right level of information about the overall program to do compiler style optimizations, especially for complex programs.
Game development has apocryphal stories aplenty about inefficient designs--e.g. the thousand-polygon model of a screw used all throughout a room, or making a ship-in-a-bottle by taking a full sized pirate ship model and scaling it down to 1% size. Usually the solution is just to stop doing that.
We will probably see more such things as the consequences of the end of the free performance lunch play out.