Startup time - thwarp!
Fighting for startup times are really pointless. So much of what we do is done via a webbrowser that I doubt most of us start the browser more than a couple of times a day. The rest of the time it's either populated with tabs and in use, or minimised/hidden behind other windows ready to be used at any point. No browser will start fast enough to challenge pulling an existing browser into the foreground.
I'm sure it's just for a bit of willy waving in an advert they have already got ready to publish.
My FF stays open for days on end. My machine gets put to sleep/hibernated at night, and resumed in the morning. The only time I restart the browser, apart from M$ patch reboots, is when it's leaked so much it's eaten too much RAM and slowed my machine up.
Even if I did start the browser multiple times a day, the alleged few seconds extra is more than outweighed by the faster page loading you get from having the ads removed.
Maybe Mozilla should target code which causes the browser to eat resources and other things which continually impact the browser usage during the course of a day, and not just a few seconds at start up?