Domain sharding on the modern web

Here is the article. 

Another interesting limit is that browsers have a total limit of concurrent connections regardless of the number of different hostnames used. This can be a major reason against domain sharding, if you consider that some browsers only support 10–17 requests max in any case.

Domain sharding is not as useful for sites with mostly static assets that do not change often, because they will get cached in the browser’s cache. The user will still feel the impact on the first load. You will get further by pushing down less Javascript, CSS and other assets to your users by making use of techniques like code-splitting, but that is a topic for another post.

Investigate where in your web app or site you are actually running into assets which are being queued because of the browser’s concurrent call limitation. It might not actually be a problem. Then, first try to reduce the number of assets before deciding on using domain sharding.

Study notes:

browser’s concurrent call limitation

reduce the number of assets before deciding on using domain sharding ...

being queued - app or site 

static assets - browser's cache 

impact on first load 

code-splitting vs domain sharing on the modern web - Spend 10 minutes to look into code-splitting