@jon@vivaldi.net OK, I tried them. They are nice to have, but for users who manage many tabs at the same time. It is not my case.

One thing I like a lot about Firefox is the about:config page. My main change is content.notify.backoffcount > 0. It stops the browser partial refreshes, and shows a web page only when its parts finished loading. In my experience, it makes the browsing faster and more comfortable for my eyes.

It could be a nice switch to have in Vivaldi too.