> In non-Latin text, if most characters are 2 bytes but a large minority are 1 byte, the branch prediction in charge of guessing between the different codepoint

> In non-Latin text, if most characters are 2 bytes but a large minority are 1 byte, the branch prediction in charge of guessing between the different codepoint representation lengths expects 2 bytes and fails very often You wouldn't want to process a single code point (or unit) at a time anyways, but 16, 32 or 64 code units (or bytes) at once. That UTF-8 strlen I wrote had no mispredicts, because it was vectored. Indexing is slow, but the difference to UTF-16 is not significant. I guess locale based comparisons or case insensitive operations could be slow, but then again, they'll need a slow array lookup anyways. Which string operation(s) are you talking about?