I tested my PR branch on 32-bit arm (raspbian bullseye) and the microbenchmark timing shows no change (within the noise across repeated runs).  Unsurprising as division is entirely different on 32-bit arm.

Raspbian uses armv6 for compatibility with the original rpi and rpi0.  armv6 does not have an integer division instruction. (how RISCy of it)  But that doesn't make a difference in this code as the final 32-bit arm ISA, armv7-a, only has a 32:32 divider.  (armv8 aka aarch64 is 64-bit and uses a UDIV as one would expect)

anyways, that satisfies me that it isn't making anything worse elsewhere.