Therefore it is recommended to delay (“defer”) the loading of non-critical files until the browser is done rendering the page. This requires adjustments to the HTML source of a page itself, as well as intimate knowledge of which file is required at what point during the rendering process. Sounds tricky? It sure is!
You may see the following recommendation from Google PageSpeed Insights:
“Eliminate render-blocking resources”
WP Rocket has 2 options to address this PageSpeed recommendation:
These are considered advanced optimizations, so take care with them and check your site after enabling them.
By enabling these options you may see an improvement in your performance grade on GTmetrix, Pingdom Tools, and Google PageSpeed Insights. Results will vary from site to site. Always remember to test the effect on the speed of your site.