I think this needs the use of a CAS (Computer Algebra System, like Mathematica) to calculate the runtime of some code relative to different choices of computer

I think this needs the use of a CAS (Computer Algebra System, like Mathematica) to calculate the runtime of some code relative to different choices of computer architecture. Then it looks practical. Could even be added to IDEs. But without the help of a CAS, few people would attempt this, because it would be too tedious to do by hand.