Nice animation indeed, but a bit too frequent in my opinion.
If it freezes, you don't have to install personas-shuffle or whatever. You only have to open about:config (type in "about:config" without the quotemarks in your address bar and hit enter), pass the warning and type "lightweight" in the provided searchbar. Among values shown, find and invert the values of both lightweightThemes.persisted.footerURL and lightweightThemes.persisted.headerURL to false, simply by double-clicking on them. Restart Firefox and now the animation should work without further tweaking.