Hello,
Please follow this article – https://xstore.helpscoutdocs.com/article/100-how-to-speed-up-my-website
Google Pagespeed (and now GTmetrix) always scores with 20-50 points mobile performance for 99% of websites built with WordPress. Try to test your site here – https://tools.pingdom.com/
Using File generator https://prnt.sc/wn70au is not obligatory.
Regards