Earlier quoted context omitted.
As an alternative data-point: My firefox session is persistent (tab are restored when I open firefox again). Apparently, I'm around 500 right now, which is a bit above average for me (I usually stay around 300). Firefox's lazy loading is very good, which means I only have 10 to 100 tabs that are actually loaded. Firefox is still fast in these conditions. Since I use tree-style-tabs, most of the tabs are neatly sorted…
You guys seriously have _500_ tabs open?!
It's kind of like saying "oh no, people are trying to do x with our platform but it's not built for that..." Well, now enough people are doing this, so it's time to change up your UI / performance.