I believe the blocking of DCL is expected behaviour for scripts with async attribute http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.htm

I believe the blocking of DCL is expected behaviour for scripts with async attribute http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.html#attr-script-async http://www.whatwg.org/specs/web-apps/current-work/multipage/... If you insert the script using a script it's execution is delayed until after DCL