When I first started using Linux day-to-day, Firefox, at least for me, was an absolute nightmare and didn't run well. I've switched to Vivaldi (Chromium-based, very power-user / I-never-want-to-move-my-hand-to-the-other-input-device friendly) for the moment, but I might just switch to Firefox again, I hadn't heard about the Multi-Account-Container feature, and that might just push me over the edge.