With hw rendering enabled, opening a single Firefox window and browsing works fine. However when I try to open a new window the browser and desktop immediately

With hw rendering enabled, opening a single Firefox window and browsing works fine. However when I try to open a new window the browser and desktop immediately become incredibly laggy and eventually unresponsive. I think I was able to successfully open a different tty and kill Firefox, which then fixed the issue, but it repro'd every time. Open one Firefox window, everythings fine. Open two, things slow to a crawl. I'm surprised you were able to get WebRender working as well, I think I recall Firefox instantly crashing when I tried that. This was a few weeks ago.