https://forum.vestacp.com/viewtopic.php?f=11&t=9790

Why Google PageSpeed Module

http://www.phpxs.com/post/2501

https://moz.com/ugc/use-googles-pagespeed-module-to-dramatically-increase-the-speed-of-your-website

Google PageSpeed Module

https://developers.google.com/speed/pagespeed/module/configuration

https://developers.google.com/speed/pagespeed/module/download

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Compiling Third-Party Modules Into Nginx
https://serversforhackers.com/compiling-third-party-modules-into-nginx

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Apache mod-pagespeed-stable_current_amd64.deb
http://www.matrudev.com/post/download-install-mod_pagespeed-linux-server/

https://www.howtoforge.com/tutorial/ubuntu-apache-mod_pagespeed/