Performance & battery · When your Mac feels slow
Why does my Mac seem a little busier just after I install Storage Studio?
Short answer: Early on, Storage Studio does one-time background work — measuring folders, building your profile and a first duplicate scan when idle. It's paced and low priority, and later runs are quicker because results are remembered.
In the first hours, Storage Studio has some one-time getting-to-know-you work to do in the background: measuring folder sizes, building your storage profile, auditing its own footprint and, if it's on, a first duplicate scan when the Mac is idle and plugged in.
All of it follows the usual rules — low-priority disk reading, a small share of what's free, easing off while you work and pausing under heavy load — so it's spread out rather than done in one burst. Later runs are quicker because results are remembered between launches.
If you want it out of the way sooner, leave the Mac idle and plugged in for a while. See Does indexing work like Spotlight?