This is a solved problem. You tackle it by doing two things: 1) use a bundler (rollup or webpack) if your code is big so it can be chunked and loaded quickly

This is a solved problem. You tackle it by doing two things: 1) use a bundler (rollup or webpack) if your code is big so it can be chunked and loaded quickly 2) have a loading spinner by default Some developers have a dogmatic zeal against loading spinners, but users are very accustomed to them. In fact, it's possible for websites to load _too_ fast, seeming unnatural to users (who at this point in time are very much expecting the flow to be request->spinner->load).