> Who cares if your backend takes 500ms to respond when it takes 5 _seconds_ to compile the JS on the client.
Frontend should never need 5 seconds and a 500ms delay on the backend seriously impacts usability. Backend performance still matters, it saves cost (fewer servers), makes scalability easier and has a massive impact on usability.
I just pulled these numbers off of CNN.com using webpagestest.org, which is showing about a 500ms TTFB and a 5 second time to first contentful paint. I'm a web perf consultant and a 10:1 relationship between frontend and backend time is pretty typical IME.
Frontend should never need 5 seconds and a 500ms delay on the backend seriously impacts usability. Backend performance still matters, it saves cost (fewer servers), makes scalability easier and has a massive impact on usability.