My Firefox is loaded with add-ons and doesn't hang or crash. And I frequently have many tabs open. Maybe one of your add-ons was causing issues.
I hear you.
I tried everything. Re-installing Firefox. Tweaking memory settings. Un-installing all my add-ons and re-installing and testing one by one. You name it. Eventually, I just said to hell with it and tried Chrome. This was 3-4 months ago, so maybe a new Firefox/Firefox Addon update has solved this.