Very often you modify some upstream file and a 100 files have to be recompiled, so in an edit-build-test loop, it's very relevant. If you only have to rebuild

Very often you modify some upstream file and a 100 files have to be recompiled, so in an edit-build-test loop, it's very relevant. If you only have to rebuild one file, then everything is already usually very fast. When you don't then that's when the 12 cores becomes very helpful. And having a PCIe SSD is already built into the mac pro and macbook. RAID 0ing a whole bunch of SSDs didn't increase build speeds for me either when we did a test. And yes, the parallelization is done as you said. The compilation unit step tends to dwarf the linking step. edit: since HN prevents a reply to the downstream comment, we did test the ram disk case and turning off swap, and comparing to an HDD. The SSD from HDD was a marked improvement, otherwise everything else wasn't that much better unfortunately. This was a few years ago for a full rebuild on a C++ project, focused on the linking step.