I would describe it like this. I go to file; I click open and then when the folder opens it spikes to 100% cpu on all 4 cores. So this happens before I actually open a file. And it’s not just a momentary spike either. It goes to 100% until I close Audacity. Very weird.
Yes, very weird, especially as Audacity only runs on one processor. (there is a feature request to make it multi-processor capable, but we don’t have that yet).
Some possibilities that come to mind:
If you are opening a file that is not natively supported by Audacity, then Audacity will be using a decoder that is on your system, which could perhaps be using multiple processors. (You didn’t say what kind of file you are trying to open).
Your security software is kicking in and analyzing Audacity and/or the temporary data files that Audacity uses. Until ruled out I suspect that this is the most likely cause.
You are not using genuine Audacity but have inadvertently downloaded a modified version of Audacity (which we obviously cannot guarantee will work correctly or be malware free).