When I look at some of my sites with https://pagespeed.web.dev I see a common theme about items that I am very hesitant to fix as they are related to the files that are bundled as part of phpBB.
Sure, I am comfortable minifying the JavaScript and CSS here and there, but eliminating render-blocking resources, reducing unused javascript, avoiding chaining critical requests, main topic work, and so forth are just beyond my scope as an end-user.
My request to the phpBB Dev Team is that before a version is launched it be placed/installed on several separate (geographically) test servers and tested with tools such as Google PageSpeed and similar, and further modified to surpass resource tests.
This would provide a better product and would make the world a better place. We would all probably live an additional 0.523 seconds given the impact, and oh what a happier 0.523 seconds that would be.