Files hangs with maxed out CPU core after duplicating many files

[Jeremy Wootten]

To produce:

Create a folder containing ca 500+ (empty) files. Select all, Ctrl-C, Ctrl-V. Files are duplicated one at a time (takes a while - progress window appears and counts down the number left to duplicate but progress bar does not work when files are empty since no bytes are transferred). When the duplication has finished (progress window disappears) Files is unresponsive and one CPU core remains maxed out.

Further investigation showed that eventually (>10 minutes) Files does become responsive suggesting something extremely inefficient is happening.