summary: if you use pinned tabs, and they're all loading at start, despite setting tabs to not load until selected, this post is for you.I have two hard disks, a 24GB SSD (fast!) and a spinner. I noticed that to fully load Firefox and wait for everything to settle, it was taking about a minute and a half, back when my root directory was on the HDD. Recently (see earlier posts), I moved my root onto the SSD. That improved things marginally. Firefox was now settling in around 1m12s. I tried moving my profile onto the SSD. Now I was down around 1m00s. (These are averaged from multiple warm runs.) That is still abysmal.
One thing I notice is that a private web app I wrote (look up My Daily in past posts maybe) is guarded by an .htaccess file, and I have it as a pinned tab. In that full minute, before things finish settling, I get prompted to authenticate myself. I then recalled that I had enabled the Firefox option to load tabs when clicked (Preferences > General > "Don't load tabs until selected"), so why is it loading?
All the pinned tabs actually seem to be loading at startup. Grr. Perhaps that is tunable?
I went to about:config, and sure enough, typing in "pinned" filtered down to this setting:
browser.sessionstore.restore_pinned_tabs_on_demanddefaulting to "false". I set it to "true", and now Firefox takes <3s to open and settle. Sure, clicking on a pinned tab now takes a normal time to load the tab, but it's better than loading GMail, Google Calendar, Blogger, Google Drive, Google Keep and my web app ALL AT ONCE.