That's not a plugin, it's a built-in feature. You can find it in Settings->Tabs: "When opening a new tab, show [The QuickDial Page]
As for Firefox, have you tried Safe Mode? If it doesn't crash then it's in your add-ons or other settings. In that case since resetting doesn't work, thoroughly removing and reinstalling Firefox might do the trick. Anyway, PaleMoon is a good choice. I had some problems with v. 25 why I reverted back to v.24 until either PaleMoon or the problematic sites fixed the problem. This proves once again the old wisdom of waiting for a month before installing any major update.