Performance & battery · Staying light on your Mac
Why does Storage Studio's background work slow down when I start using my Mac?
Short answer: Storage Studio deliberately shrinks its background work while you're typing or clicking, then catches up quietly once you step away, so it never competes with your own work.
On purpose — your own work always comes first. Storage Studio keeps reading how recently you used the keyboard and trackpad, and while you're actively working it shrinks its background budget to a small fraction so you don't feel it.
Once you've stepped away for a little while, it lets itself catch up quietly, and it allows itself a bit more when your Mac is plugged in than when it's on battery. The result is that things like building your storage profile or measuring folder sizes may finish a few minutes later than they could — Storage Studio has no deadline, and it would rather be late than in your way.
Anything you start yourself, such as Scan now in the Duplicates window, isn't treated as background work.