As stated by mu colleague Arjan van IJzendoorn on a related forum issue, 92883:
The issue occurs if the project has (a lot of) excluded documents. There is an accidental slow-down in the rendering of the project explorer tree which only happens if you have excluded documents.
We are indeed working on 7.23.1 to fix this.
If you do not have excluded documents, you can keep on using 7.23.0.
Hello All,
We have indeed received a couple of tickets regarding this issue. We are looking this with the highest priority. We will communicate through the tickets.
With kind regards,
Feddo van Ede Technical Support Lead, Mendix Support
https://forum.mendix.com/link/questions/92868
Someone here has an issue with 7.23, but it doesn't sound similar to yours
Yes, I have this issue also.
I've already filed a support ticket for it…
//Edit: Shared my project MPK with support. Hopefully they'll what's wrong. Currently, 7.23 is unworkable due to the modeler going unresponsive after every ‘Run locally’ action, or even after a save action on a document.