No way are they more performant than native apps. Their big advantages are write once run anywhere, no vendor lock in, easier install, and more control, privacy and sandboxing since they are web apps.

If performance means performantly hogging resources performing the most basic of task, then sure.

That's the reason to choose PWA over other web technologies, not native.

What other technologies?

I'm assuming they're talking about a standard SPA (or even a conventional full-page-reload web app), or React Native or Electron on the desktop or similar. In the former case, a PWA can use service workers and caching and so on to get better network performance. In the latter case, they can leverage a preexisting Chromium/other browser instance to get most of the advantages of "write once, run everywhere" without bundling a whole browser instance with your app. I can't wait for full PWA support in Firefox, especially on desktop!

Could you elaborate on that? Performance of what exactly?

Loading times and responsiveness.

For example, Twitter’s native iOS app is about 115 MB, while their PWA is a tiny fraction of that, probably not more than a few MB. This unsurprisingly reflects on performance.

Wow thats huge. I haven't used twitter in years, I wonder if it was always so bloated.

It must be performance of your developers being able to develop for one codebase.