Back to front encoding is fastest

[oscbyspro]

UnsafeMutableBufferPointer has a nice API for setting elements font to back, so you might shoehorn the implementation in that direction (as I have done). In doing this, you have to perform some wizardry because the characters are extracted back to front by a remainder operation. Going the other way turns out to be faster.

[oscbyspro]

(radix == 10): 5995 -> 5620 (1.07x)
(radix == 16): 2868 -> 2440 (1.18x)