The patch notes mentions all that new, fancy UE5 tech, so it's no wonder it's running worse. I don't know if it's looking better at the same time though, so you might be able to turn down some settings, and not lose as much performance.

Also, it's the experimental branch, so it's likely they'll fix bugs and improve performance somewhat.

I haven't played in a while, maybe once it gets released to the stable branch and mods are updated I might give it a shot.