People are reporting "Settings API is slow". Let's document and investigate, with this meta bug to keep an overview.

Note that I'm especially concerned about the synchronous performance of calling `mozSettings.createLock().get()`. I don't really mind if it's slow to call asynchronous callback. But the synchronous performance is essential because we have a lot of libraries that are simply running this code when being merely inserted and executed, and this hurts application launch performance.

(In reply to Julien Wajsberg [:julienw] from comment #1) > Note that I'm especially concerned about the synchronous performance of > calling `mozSettings.createLock().get()`. > > I don't really mind if it's slow to call asynchronous callback. > > But the synchronous performance is essential because we have a lot of > libraries that are simply running this code when being merely inserted and > executed, and this hurts application launch performance. Do you have a profile where this shows up? This shouldn't be a performance bottleneck at all. We just create an object and put it into a queue. Everything happens async behind the scenes.

I don't trust our polling profiles, too much noise, too random things, we can't see anything. See bug 1122649: I posted there a debug patch I used to find this issue. Let's move this discussion there.

[Tracking Requested - why for this release]: