Unresponsive, Laggy UI (Score 1)

In Windows, I can have all kinds of Firefox tabs open, and switch between them while one is loading. In the latest Ubuntu (and all other versions of Linux that I have tried), I cannot do this. Firefox is far less responsive in Linux than in Windows. Even scrolling on a page with a lot of text can lag Firefox in Linux. In Windows this doesn't happen. There are also other apps where this is the case. Can anyone explain why this is? I haven't found a good answer on this.