I did it here implementing the Chinese whispers benchmark using OCaml threads (with mailboxes) and Lwt. Here are the results, for 100k threads:
OCaml threads : 1.581s
OCaml Lwt (fast) : 0.007s
OCaml Lwt (slow) : 0.111s
Go go-routines : 0.952s
Since Lwt doesn’t suspend a ready computation I had to implement a slow version of Chinese whispers, so that we can indeed measure the performance of the Lwt scheduler. In any case, even a slow version is 10 times faster than Go, and goroutines are only 1.5 times faster than POSIX threads in OCaml.
As it is said in the SO post, the implementation is following the style of the benchmark, so real Lwt code would be even faster, as usually, you don’t need to use these mailboxes or artificially prune Lwt optimizations.