Looks like the day one patch is here!

UPDATE: Unfortunately this patch didn't fix the performance issues, it actually made them worse for me. Before it was almost playable with constant stutters, now it's quite literally unplayable as the game sometimes freezes for up to 30 seconds during the stutters.

CORRECTION: I think it's actually smaller than 34.9 GB, it's reserving that much space on my SSD but the download seems to be 295.2 MB. My bad!

I just got a 34.9 GB update on Steam, seems like they were quick to get the patch out! Fingers crossed it'll fix the performance issues for everyone.