> I've been using it for some of my work for a few months now, after a multi-year hiatus because it always, no matter which version I installed, slowed to a crawl after a short while of use.

I am surprised to hear this. I had this complaint a few years ago too, but today, I currently have about 105 tabs open right now, all fully loaded and it's running fine. I am running on an Apple Macbook so maybe that's the difference? I run Chrome and similar number of tabs result in my fans turning into jet engines.