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I've been looking at this site: https://varvy.com/performance/ and am confused on where blocking css / JS loads are measured. Is it between domLoading & domInteractive or between responseEnd and domLoading?

Matt Westlake
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So I finally got a little clarification, and the answer is... "It depends". Looking at http://www.growingwiththeweb.com/2014/02/async-vs-defer-attributes.html

If you use a plain script tag, it will block inline during the parsing of the html.

If you use DEFER, the blocking bit will always happen after the HTML is finished rendering.

If you use ASYNC, the blocking bit can happen at any time (during the HTML rendering, or after depending on how long it takes to download), but BEFORE

ALSO: reference Script Tag - async & defer

So unfortunately there is no easy answer.

Matt Westlake
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