I have a simple html/css page that is considered 'poor' with Google's PageSpeed Insights.
It says to
Your page has 8 blocking CSS resources.
Leverage browser caching
Setting an expiry date or a maximum age in the HTTP headers for static resources instructs the browser to load previously downloaded resources from local disk rather than over the network.
Prioritize visible content
Your page requires additional network round trips to render the above-the-fold content. For best performance, reduce the amount of HTML needed to render above-the-fold content.
Please edit the files to deliver the highest speed rating with PageSpeed Insights
I will send you the files.