I'm bad for having a lot of tabs open. At home I have easily 100+ sitting in firefox. I have a bad habit of seeing an article or something that I want to revisit later and archiving it there. "So use the history feature instead". That only works if you remember the name of the site or article. "So use bookmarks". I like to keep my bookmark list small.
The current firefox doesn't load all those tabs on startup anymore anyways, only when you click on them. So other than the overhead of listing all those tabs at the top it shouldn't cause performance issues.