macOS Big Sur very slow to open

Hello !

I recently went from macOS High Sierra to macOS Big Sur on my Macbook Pro because I needed the update for some of my softwares.

Since the update, my mac is very slow to load the user session.
When starting my mac, it goes to the page where I can choose which session to load fairly quick. Then, when I choose my user session, it takes from 10 to 15 minutes to load, with the loading bar stopped half way.

Is this a known issue ? I can’t seem to find a way to fix it.

Thank you.