[syntheweave]

As the number of code paths go up, the percentage of run-once code does too. Most findings agree that optimization increasingly tends towards a small number of hot loops which could benefit from hand optimization.

In modern codebases his has the effect of micro-optimization of the "rewrite in assembly" sort mattering a great deal in heavy lifting library code like codecs, CPU emulation, rasterizers, VMs etc, and not at all in other areas. Emulation is a decent candidate in this regard but it also massively benefits from higher level simplifying assumptions(e.g. not polling for I/O changes at the true device frequency). It can be hard to notice differences in emulation quality where high level techniques are applied well.

On old 8-bit architectures it was rather the opposite: you couldn't be high level about anything because you had to design towards micro-efficiency. Therefore most of your problems were solved with very simple data structures and algorithms that heavily favored either space(by recomputing the intermediate results) or time (by precomputing all answers in a LUT), and then given a very tight cycle-shaving, code-golfing implementation.