Even something as simple as wc calling a libc function for parsing utf-8, that doesn't get inlined, would destroy its performance relative to anything optimized.
Personally, I'd expect SIMD to win over all of these. wc sounds like kind of challenge that's very easy to partition and process in chunks, though UTF-8 might ruin that.
Which counters to increment at each byte depends on the previous bytes, though. You could probably succeed using overlapping chunks, but I wouldn't call it very easy.
That sort of "find the correct chunk boundary" logic was very common with all the mapreduce processing that was done when people still used the phrase big data.
