For whatever reasons most of my software (desktop and servers) ends up having this "heavy crunching" part in it be it. I usually do not create products that only serve as a simple conduit to a database.

Neither do i (in fact i use Delphi and Free Pascal for practically decades now and i never touched a database :-P) - most of my stuff are graphics and geometry related and yet i haven't seen much of a difference between my C or C++ and my Free Pascal (which AFAIK has worse optimizations than modern LLVM-based Delphi) code. Of course i refer to optimizations based on the generated code, algorithmic optimizations are another topic.

The only time i saw a difference when i made a raytracer benchmark[0] explicitly to benchmark the codegen where the Free Pascal codegen at its best was at 177% of the speed of the Clang 8 at its best. In my experience this is not a realistic metric though (according to the benchmark my C 3D engine should be five times slower if compiled in BC++ than Clang but in practice since it does a variety more stuff than just a single thing the performance difference is barely perceptible).

[0] http://runtimeterror.com/tools/raybench/