It just suddenly happened. I was caught unawares. Firefox decided it needed to eat up all my RAM and suddenly, behold for all my RAM was eaten up by Firefox (it took up about 1.5 GB of RAM.

I didn’t have the chance to take the screenshot with Firefox process in it though. A pity. Is this a memory leak? Or perhaps a software bug? I don’t know. It has happened only once though. We shall see.