The folders that I'm comparing have about 20K files in them and several hundred folders. When it works right, it takes 20-30 seconds. I turned on the machine tonight for the first time in a week and I immediately got the "Folders seem identical" message. I know that I added files to my subfolders during the week. Also, there was no chance for a cache to be created, which can make it go faster. The 'include subfolders' is, of course, checked.
I tried repeatedly clicking Rescan (F5) and it doesn't work. I'm starting it from a .BAT file. The line being executed is:
"C:\Program Files (x86)\Synchronize It!\wndsync.exe" d:\Files\Work n:\Files\Work /scan /r /date
Thoughts? Anything else I can check?