Today I had a problem which I thought was related to having the extended attribute com.apple.quarantine on a folder with a large number of files and subfolders.
In the end, I had removed the quarantine from them all (topic for another post). It wasn’t the source of the problem at hand, but it did wind up with an important lesson: remove quarantine from any .zip file before decompressing it. Apple’s “Archive Utility” (the program that does the decompression) will maintain the quarantine attribute through every file, directory, and sub-directory.
If you’ve got a directory with a huge number of files set with this, look for my blog post on removing them all.