So I GM's a campaign for a year in Roll20 and things started to bog down. The system got slower with the accumulation of maps and tokens. So I created a new campaign and brought the players over to that. That was a bit of a hassle. Roll20 lets Pro Users transfer elements from one campaign to another so it wasn't too bad, but still I had to send out new links and more than one player logged onto the old link out of habit. So its not really ideal. Then that campaign started slowing down, NPC character sheets weren't opening and it was just a headache and I considered starting the new campaign migration again. Then I had that moment of clarity where I decided why move the players when I can move the maps and shit. That is the idea of a Campaign Backup.
So you have the campaign you run, and a second campaign where you transfer maps and tokens and things you aren't using very often. So they are backed up so to speak and you can delete them from your main campaign lightening the load. Since you aren't playing in the Campaign Backup it doesn't matter how slow it gets and you can transfer maps or tokens or whatever back to the original campaign with ease. Players don't even need to be aware of that sort of thing. You could even use a single backup for multiple campaigns assuming they used the same RPG.
Nothing world breaking but it solves some problems nicely.