Of course, loc is a bad goal for productivity, but it can still be an interesting measure (similar to test coverage): If I count lines of code added, commits, or tickets closed, I cannot compare any two developers. But if I count that metric for the same developer, or the same team, I can certainly spot changes in productivity. (As every metric has its outliers it would probably be. best to combine all of them.)
So if I was managing a team and wanted to know if it would be beneficial to optimize test execution times, I could just rent some bigger machines and see what happens. I could also do a similar experiment with organizational aspects like the size and schedule of meetings or the introduction of a dedicated on-call contact for support requests, etc.