Freeing up space · Free Up Space wizard and button
Why does the freed figure lag behind while files are still moving?
Short answer: Each item's space is only released after its copy is checked, so the freed figure catches up as each item completes. It shows space genuinely returned, not a prediction.
Because copying finishes before the space is released. Storage Studio only frees the original once the copy on your fast drive has been checked, so for each item the freed figure jumps up at the end rather than climbing smoothly.
The progress view reports space genuinely returned on your disk, measured — not the amount it expects — which is why it can look slow mid-run. It says so on screen so a lagging number doesn't read as a failure. At the end it compares the real result with the prediction and tells you plainly if it fell short. See why less was freed than expected.