It would be good to implement something like this, similar to Microsoft Edge. This would help to decrease the amount of time it takes for Firefox to start up.
I don't want any fake quickstart features which just hide loading during the system boot process. This makes booting slower and brings background processes sitting around all the time. This is a resource hog and not desireable in terms of minimizing attack surface for security reasons.
The only proper way to make Firefox start faster is to optimize the process for efficiency or make it more slender.
Wouldn't you guys like a Fast Startup feature for Firefox?
What the feature should do: It basically preloads Firefox on Windows Startup. Thats all. If you open Firefox it'll start very much faster. Maybe you know that concept already from Microsoft Edge, I think they call it Startup-Boost.