Hey I didn't know about shift-rightclick. For me, disabling dom.event.contextmenu.enabled gives me both menus at once, then I tap Alt to get rid of the browser's menu if I want to use the app's menu underneath it. But I won't have to do that anymore.
This is a blunt tool. Some sites uses context menu events in a benign way. A better alternative is to simply bypass context handlers with shift-rightclick when necessary.
> webgl.force-enabled
This isn't really a performance improvement. If webgl is disabled it's due to troublesome drivers. Forcing it on can crash things.
> layers.offmainthreadcomposition.enabled = true > layers.offmainthreadcomposition.async-animations = true
Those are the defaults anyway on supported platforms