Hello, First I have cleaned the inlining instruction and get better result leting flambda deciding alone. This leads to 36s with 4.13.1 sequential 36s with 4.12.0 sequential 32s with 4.12.0 multicore (but not using any parralelism) So being more reasonable with inlining annotation yields no more changes between 4.13.1 and 4.12.0. Still I am surprised that multicore is better (should expect a bit worth ?) > > Christophe: please put your benchmark online somewhere so that we can make our > measurements.  Without reproducibility, your initial message is useless.  > Thanks. The code is there (it uses functors a lot, could be a good bench for flambda): https://github.com/craff/hypersurfaces.git and depends from (opam version might not be sufficient) https://github.com/craff/gles3.git https://github.com/craff/pacomb.git and other opam packages. If you "opam pin ." the three git repos above everything should work. The command to test: dune exec --release Hyper -- tests/hard/hilbert-sextic.txt -b It prints its own timing as below among other messages: total: 36.329s ( 0.012s self) for 1 call(s) You can use other files in tests or tests/hard. > - Xavier Leroy > H