Bitcoin doesn't use base-58 in any performance relevant way, it's only used for user interfacy sort of stuff. Probably the most straight forward way to make fa

Bitcoin doesn't use base-58 in any performance relevant way, it's only used for user interfacy sort of stuff. Probably the most straight forward way to make fast base conversion is the way that most range coders in compression (which are effectively just fancy mixed-radix base converters) do it-- first store temporary digits of a larger size so that the there won't be any inter-digit carries, then make a second pass through to propagate the carries and generate the output. IIRC the approach in bitcoin core is related-- but it processes the carries eagerly rather than deferring them (which makes it asymptotically quadratic (the worst case), but the average case is fast).