For the spectral-norm one I think it's a failed attempt at parallelism. This code spawns 4000 tasks:

    parallel:
      for i in 0..<n:
        spawn times_i(v, u, i, n, reverse)

(https://github.com/hanabi1224/Programming-Language-Benchmark...)

It's almost four times as slow as the otherwise identical single-threaded version.