What can be reason for slow content downloading from webserver?
Solution 1:
The answer to this question is that script has a source map available. With Chrome's Developer Tools panel open, it makes transparent requests to any available source map files (which it does not show you).
These files are often absolutely massive (mine are 3MB+) and take considerable time to pull on every refresh. Nginx specifically also handles them very poorly, at least in my setup. I think setting the max sendfile chunk size to be lower helps.