Probably no one really cares about the speed of a web page loading, but search engines do.
I use my phone’s quota limited data plan as a hotspot for my laptop because I live in a rural area. I got the text saying it would renew today, so I went ahead an watched a movie, that ate up the last of the quota, and so now I am on the super slow 128b/sec “unlimited” portion until it renews.
I went to the WP forums and as it is almost all text, it didn’t seem any different than normal. I had to look up something on their Make blog for an answer, and that took awhile to load (every latest post and all comments on one page).
Then I came here, and it took longer than the Make blog to load. It seems like this is mostly text, like the WP forums, but it is a lot slower.
Anyway, I’m not sure that there is anything to fix, but it’s interesting to me that it’s slow loading.
I’ve never seen the prompt (chrome on Android) but I think is not a forum problem but some setting on my phone because I’ve just tried with another site I’m sure offers PWA and same problem.
(Luckily ) I’m on holidays without a computer to investigare further.
As far as I’m concerned, the page speed isn’t that bad, both on mobile and desktop, I don’t have Progressive Web App. Does it reduce page weight? Yes and No. No, because it downloads necessary stuff at first load, and Yes because, it becomes faster whenever you visit again (thou it depends on how it is implemented, but I bliv it should rock).
If you don’t want to use it in on your mobile phone, give the desktop version a try - click the plus icon at the rightmost part of the address bar, here
I think using an app for every site that has one is a huge step backwards for the web.
All this topic is about is the speed difference in this forum which uses a 3rd party tool, and the WP forums which use WP. (and a little about the slowness of the WP Make blog which also uses WP)
I think my take-away is that text is fast, and limiting resources loaded (images and javascript) is also fast.
This is also true for the web version of Discourse. Once you’ve loaded the initial page, clicking links doesn’t actually do a full new page load, it just loads in the new content via Discourse’s JSON API (and any images in the content after that).
Creating a “single-page app” like this and actually having it be worthwhile (faster than just doing normal page loads) is very difficult, but I think Discourse is one of the few projects that has cleared the hurdle where it is really worthwhile for them to avoid any new page loads and build mostly using JavaScript.
) I’m on holidays without a computer to investigare further. 
