Scanning, hashing duplicates, comparing photos, and calculating folder sizes can use CPU, memory, and disk while active.
Confirm active work
Check whether progress is moving and which tool is running. Resource use should normally fall after the operation completes or is cancelled.
Reduce demand
Scan a smaller folder, raise minimum-size thresholds, close unrelated heavy apps, connect power, and avoid running several file comparisons at once.
Persistent use after completion
Quit and reopen diCleaner. Restart the Mac if a process remains. Update to the current edition and reproduce with a small test folder.
Memory pressure
Large result sets can require memory. A low duplicate or similar-photo threshold can include many small files; restore defaults and rescan.
Report
Include the tool, scope, thresholds, duration, approximate file count, and a redacted Activity Monitor sample when requested. Do not send private files.