Why does Firefox eat up 1 gig of memory?

Question

Mozilla Firefox

The computer started to hang when I work on webstorm (IDE) and open the localhost in Firefox. It turned out that the browser starts to eat memory very strongly, in other browsers this is not the case. It seems that the problem appeared when I used the key for webstorm, found on a pirate site. I deleted the key, reinstalled webstorm and firefox, but the problem remained.