Sortperm is slow; Julia's oldest performance issue(s)

Continuing the discussion from 10x faster sortperm(): Sortperm is at least 77.6% slower in Julia than in Python/NumPy. Note, this is known, the next oldest performance issue (and third oldest issue from 2013): [It’s similar in speed for Float64 and Int64 as expected, but it doesn’t go much down with smaller types down to Int8 (nor much with NumPy), a bit surprising, because of radix sort?] We are not (no longer?) “3x slower for sortperm” (as once for MATLAB in 2013, but I didn’t test it, as...