I wonder if there's a worthwhile time-saving in aggregate? To me it seems like overall the bottleneck is always thinking what code to write/edit, not the actual edition. So I'm not convinced shaving a couple seconds here and there outweighs the benefit of a modern IDE or offsets the time spent ricing such a setup.
It's not mainly about speed (although the ceiling is much higher), but about ergonomics, and, plainly, enjoyability. The other benefit of making your own environment is mastery and control; only you can decide when and how the environment changes.