When it comes to PGO (vs. profiling the whole system) though it's worth noting that a lot of the speedup comes from things which are too trivial for us humans t

When it comes to PGO (vs. profiling the whole system) though it's worth noting that a lot of the speedup comes from things which are too trivial for us humans to consider. When I profiled the D compiler with and without PGO enabled it became obvious that a lot of the speedup of PGO basically comes just from running the program, the choice of testcases made almost no difference.