We have built the DES Y3 galaxy cluster analysis code on a Mac laptop twice, once using the GCC compiler suite in a Docker container, and once using the Apple clang compiler natively. We run the same pipeline (snapshot_test.ini), and collect timing results, shown below.

The timing labeled gcc was run in a Docker container, using the C, C++ and Fortran compiliers of the GCC suite, version 7.4. The timing labeled clang was run natively, using the C and C++ compilers from Xcode 10.3, and Fortran from the GCC compiler suite, version 9.2.

The deltasigma module spends most of its time in compiled C code. The camb module is mostly Fortran. The sigma_r module spends most of its time in numpy, which is compiled C code.