There is ongoing discussion [1][2][3] to enable more aggressive optimization for "Flambda" switches, in some cases this can bring more than 2x times speedup.

[1] https://github.com/ocaml/opam-repository/pull/16753

[2] https://discuss.ocaml.org/t/ocaml-4-11-first-beta-release/60...

[3] https://discuss.ocaml.org/t/ann-bap-2-1-0-release/5906/9