Does the duplicate scan slow down the regular scan in RJL System...

The duplicate scanner is designed to add minimal time to the regular scan. The two-pass approach (size grouping first, then hashing only matching files) means it avoids reading the full contents of most files.

On a typical computer with an SSD, the duplicate scan adds a few seconds to the total scan time. On computers with a large number of files or a traditional hard drive, it may take longer -- up to 30 seconds in some cases.

During the duplicate scan, you will see progress text: "Scanning for duplicates: checked 12,847 files..." so you know the app is working.

The scanner caches file hashes between sessions, so repeat scans are faster -- only new or modified files need to be re-hashed.

If you prefer not to scan for duplicates, you can uncheck "Duplicate Files" in the sidebar to skip it entirely.