Add below code your WordPress theme functions.php
or try to user wp plugins scripts to footer (this not moves script in the mobile version of mobile.
speed booster pack move all the script but not allows to minify HTML.
HTML loads first, so the user can see what they want. js Loads meanwhile.
just look at the Adsense ad code <script>
<script async src=”path to js file”></script>
this is deep process only for developers. 90% of people ignore this.
Another thing is Optimize CSS Delivery
Minify CSS: Reducing the size by removing comments & Space This process applicable for JS and HTML too.
CSS Placement: why we have to place CSS in the header. Without CSS Plain HTML Loads it looks like ugly.
Inline CSS: if there is small CSS then try to inline the CSS instead loading from external file.
The best Plugin to cache all resources and serve quickly w3 total cache.
Check out my other thoughts Increase page speed score in google insights 95+, How to improve page speed