My answer won't directly answer your question, but will address the concerns of many. The Google PageSpeed Insights is a good tool - however, it is too good, and it requires perfection, which is very seldom achieved on real websites. Case in point: YouTube.com has a score of 54 for desktop, and is failing on mobile. Amazon.com has a score of 50 on mobile and 60 on desktop. Twitter.com has a score of 60 for mobile, and 37 for desktop. We are talking about 3 super major websites here.
Google.com gets a score of a 100, but that is because it is returning a 503 error to the tool, and is asking for a verification code.
I'm not saying that one should completely ignore the score and the advices of Google PageSpeed Insights, but what I recommend is that people shouldn't take it extremely seriously. A score of 80 (even 70) is good, as score of 85 is wow. If you're at the point where you are breaking your website just to make sure you have a good score, then maybe you have gone too far...