Can the Microsoft Edge "Startup boost" interfere with extensions?

[Juraj M.]

Some Chromium browsers have a feature that "speeds up" start time by keeping browser running (or part of the browser?). For example Edge or Opera and maybe Chrome on Chromebooks?

I wonder what's happening in the service worker of the extensions - are they running? For example will alarm fire when the browser is "closed" this way?

[wOxxOm]

You can verify it by storing something in storage in an alarm. Without trying it myself I think it'd be a bug because only extensions with "permissions":["background"] should be kept running after the last browser window is closed. 

[Juraj M.]

Thanks! 

But now have even more questions :), I need to read about the "background" permission because I've never heard about it.