He's doing "one-way synchronization of directory trees In Windows". If that means he's doing archiving, he only needs to compute the MD5 of the archived file once. That means that MD5 requires that one file be read fully, whereas File::Compare requires two files to be read in part or in full.

In reply to Re^3: Best practices for file synchronization? (Mod time vs. contents compare) by ikegami
in thread Best practices for file synchronization? (Mod time vs. contents compare) by OfficeLinebacker

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