With a relatively large CMake project (10k source files/targets), right-clicking on a file in the project tree and selecting "Open in Finder" freezes the QtC UI for about 10 seconds (or longer). The macOS Spinning beach ball cursor is shown the entire time. After that period, Finder opens and shows the file, and Qt Creator is usable again.

I checked on the exact same system with the exact same project and Qt Creator 4.13.0  also suffers from this freeze. Version 4.12.4 does not, and the Finder window is shown within a second of clicking the right click menu action.

This does also not occur on Windows with any version tested.