I always use binary interchange formats between programs so I am not familiar with the overhead caused by format conversions. Even when displaying numbers for reading them, in the case of floating-point numbers that are displayed in the "scientific" format, i.e. with exponents, I prefer to have only the exponent as a decimal number, but the significand as a hexadecimal number. So I do not need fast algorithms for number conversions.

Nonetheless, there are plenty of people who advocate the use of JSON, XML and similar formats, in which case I assume that number conversions can take a non-negligible time, which might be decreased by such fast algorithms.