impossible to work on Premiere Pro Beta

I work on a (heavy) documentary project for months. Until days ago I was on Premiere Pro 23 automatically updated.  I then installed PPro Beta using the enhance voice that worked perfectly well... But from  then on it get worse and worse: first very slow to process any editing  action, even the most basic to just read the editing, and now the situation is that the project opens but then it takes like 5 minutes for seeing the image from the last editing point on the timeline to appear on screen, and then nothing more happens... impossible to read or do anything, it's blocked.

I also updated the MAcOs, being now on Sonoma 14.0. 

I work on a MacBook Pro 2022 / Apple M1 Pro

I have reimported the project in a New Project, but nothing changed.

Thank you for your help!