Perf cache

[quantizor]

adds the new cache functionality on top of #547

base
adjusted, size 500

Rationale for increasing cache size is the partials it's storing are quite small and a medium-complexity website may have thousands of them. They probably won't take up much space even in volume.

>19% improvement in the cached example, essentially 10% better than the original PR.

15% of the overall total improvement in the cached example specifically is directly attributable to the cache (I also tested the cache change against main specifically with no other adjustments.)

[quantizor]

@dcastil split the cache change out and added some more perf notes