Thread freezing GUI

[marcel]

There is, however, another Widget-based plugin that I connect to sub threads whenever I create them.

By connect do you mean at connecting them to the started() signal of a thread, I assume.

The bottom line is that no widgets must live in other thread than the GUI thread.
Qt::AutoConnection means Qt::QueuedConnection if receiving object does not live in the emitting thread, and Qt:irectConnection otherwise.

You said that the threads are performing IO operations.
I assume that they will read something from some device and update the GUI accordingly.
A problem could be the rate at which you're updating the GUI.
Sending a lot ( and I mean a lot ) of signals from the worker threads to the GUI could put some heavy load on the GUI's event handler.

Regards