Firefox 57 beta performance

I’m using Firefox 57 since Nightly and it’s a suge improvement but lately with the beta I’m having performance issues. It’s using a lot of RAM >5gb easily and starts to freeze temporarily, not charging pages or charging it very slowly, etc… It happens to me in two different computers/profiles, at work and at home.

I’m not filling a bug because I can’t give much more details, it’s only a (bad) feeling that I’d like to know if someone can corroborate.