I only have 2, and no, they won't be coming off. AdBlock Plus and NoScript are too essential. If they are really issue causing, perhaps Mozilla will write the browser to address the pains these two address. Happily, my must have, TabMixPlus, and the 4 other niceties are NOT on the list.
I can say, however, I have used many of them, and I do agree - many of them slow it A LOT! Read it Later seemed particularly onerous given what it does. That one got removed shortly after it was tried.