Weston,
I did a little investigating and here is what I found:
(1) The one file that has been loading slowly on my blog pages is https://www.ocalahomes.online/wp-admin/admin-ajax.php. This file averages about 3.0 seconds to load. However, I could find nothing in the literature that pointed to the Rest API as a possible cause. The file is primarily used by the WordPress Heart Beat feature. Therefore, the most common fixes recommended were to reduce use of the file by Heart Beat and, if necessary, troubleshoot other plugins that use Ajax. In doing the troubleshooting, I discovered that the plugin I use to generate my blog pages was the cause. When I deactivated it, the ajax.php file loaded instantly. However, that plugin allows me to load all blog pages, both mobile and not, in AMP mode. Since the AMP blog pages fully load in 800ms on average and I don’t use non-AMP blog pages, I reactivated the blog plugin.
(2) That brings me to the issue of your PWA plugin. As I mentioned before, the SuperPWA plugin loads without the slow loading manifest file issue. For various reasons I like your plugin better and would love to use it. But I can’t justify the sacrifice of page load speed. If you do ever resolve the manifest loading issue, please let me know. I would be excited to start using your plugin again.
Thank you,
Andy