With HTTP2 support this is not longer really a problem, since HTTP2 multiplexes requests over 1 connection.
Re:To www or not www
by jrochkind1 on Sunday March 19, 2017 @01:23AM
(#13905390)
I think few web apps (aka software driven sites, not just static content) use http2 yet.
I believe the Chrome connections per host is now 6 (even under old school http). Not sure about the other browsers.
If you are using Websockets or AJAX the connection limit can become an issue.
Also some users always write www in front of the domain. Although some browsers will just redirect to Google. So if you check browser referer a lot will be from www.google.com?q=www.yourdomain.com