Nolan LawsonNov 27

"The top-line takeaway is chilling: sites that are explicitly designed as SPAs, and which have intentionally opted in to metrics measurement around soft-navigations are seeing one (1) soft-navigation for every full page load on average."

Amazing research and analysis as always from @slightlyoff https://infrequently.org/2025/11/performance-inequality-gap-2026/

The Performance Inequality Gap, 2026

Embedded in this year's network and device estimates is hopeful news about the trajectory of devices and networks. It has never been easier to deliver pages quickly, but we are not collectively hitting the mark. Indeed, the latest CrUX data shows not even half of origins have passing Core Web Vitals scores for mobile users. Browsers will need to provide stronger incentives. This will be unpopular, but it is clearly necessary.

Alex Russell
Show threadNolan LawsonNov 27

@slightlyoff Frankly I'm skeptical of _all_ claims of SPA superiority:

- Paying for slow initial load is amortized across subsequent soft navs
- Soft navs are faster than hard navs
- Any of this is worth breaking the back button

You can always point to one SPA where it works, but in aggregate it doesn't seem to be working.

Show threadThomas Steiner Nov 28
@nolan Can you point out one SPA where it actually works well indeed? I'm always so frustrated by GitHub, where even on a WiFi network it's often faster to right-click and open in a new tab.
Show threadSimon Eilting

@tomayac @nolan I can't demonstrate it but I used to work on an internal tool that worked very well as a SPA. Every user was on a fast PC with a fast connection, so initial load times were almost instant (and the time to load the working dataset an order of magnitude higher), and we saved a lot of developer resources that way.

Now I can't point out one that's generally available and meant to be used on mobile phones. I don't think it's commercially viable to build that.

Nov 28 at 9:46amWeb
Show thread1.3.6.1.4.1.61513Nov 28

@eseilt @tomayac @nolan I work in edtech and our users, students and teachers, click through a lot of content and assessments and exam pages in a single session.

HOWEVER, what we currently have leaves a lot to be desired.

One specific issue is bundles being bigger initial load time is naturally slow. Now think about a class room full of students trying to load that up at the same time. It's very easy to bottleneck even a modest connection.

"But we have a service worker that caches it", except because of our amazing* developer practices we are doing several releases a day which invalidates the clients caches...

Show threadSimon EiltingNov 28

@xssfox @tomayac @nolan yeah, caching of app bundles is definitely not a thing in 2025. You only get that for stale apps that don't see active development.

But to be fair, the same is true for SPAs - "it's in the cache" is an argument from the days when development happened slower and unencrypted HTTP was in use.

I'm not saying SPA is a great idea for all internal use cases, for sure. Just that it can sometimes work out.

Show thread1.3.6.1.4.1.61513Nov 28
@eseilt @tomayac @nolan I did have a bit of a cursed thought about our very specific edtech use case in which we could use webrtc to distribute content between students on the same network/school...
Show threadSimon EiltingNov 28
@xssfox @tomayac @nolan slightly modified bittorrent client in WASM. It's not overengineering if it solves* a real* problem!