This "leagues ahead" is simply not true experimentally. I ran the Polyhedron benchmarks on SKX with profile-guided optimization. Pre-release gfortran 10 was (i

This "leagues ahead" is simply not true experimentally. I ran the Polyhedron benchmarks on SKX with profile-guided optimization. Pre-release gfortran 10 was (insignificantly) faster on the bottom line than beta ifort (from oneapi). That was reversed for gfortran 8 v. ifort 18. It's also not true that HPC performance is generally dominated by code generation rather than libraries and communication costs, but obviously mileage varies.