> ... it's hard to imagine this making a big difference in any real use case, offline or real-time.
Google once, back in 2013, made an API change to their v8 engine because it saved a small handful of CPU instructions on each call into client-defined extension functions[^1]. That change broke literally every single v8 client in the world, including thousands of lines of my own code, and i'm told that the Chrome team needed /months/ to adapt to that change.
Why would they cause such disruption for a handful of CPU instructions?
Because at "Google Scale" those few instructions add up to a tremendous amount of electricity. Saving even 1 second per request or offline job, when your service handles thousands or millions of requests/jobs per day, adds up to a considerable amount of CPU time, i.e. to a considerable amount of electricity, i.e. to considerable electricity cost savings.
[1]: https://groups.google.com/g/v8-users/c/MUq5WrC2kcE