The files would be separate for each snapshot, so you are only working on one file at a time, performance will be the same as it is now. Video recording is not really a problem either, it will not record a video for each file separately, only one for the „master file“, which includes all your work for each versions, which is exactly the same as trying multiple versions of your work without my suggested snapshot feature.
That is basically the same function that you described with the layer, except that this layer would show up in a dedicated panel (or actually it can stay in the layer panel but look different, like a different color or an additional icon that shows it is a snapshot and not a normal layer) and that you can „reactivate“ because a full Artstudio pro file is backed up together with that snapshot layer.