[ilyt]

> Why does Python do all this? So that you can have O(1) character indexing. If you gave up on that, you wouldn't need to convert the string at all, you could just leave it as (potentially invalid) UTF-8 data.

Seems like "giving up" would've been better choice, considering just how rare operation that is. Or alternatively doing the conversion lazily the first time operation needing runes instead of bytes happen.

Most string operations are not accessing string by index and most of them even at O(n) would be fast enough because n is small. Like in typical "get a file name, extract some info from it", you're doing extraction once and anything after that doesn't need character indexing, because you already got the relevant data.