Some user reported long boot times, so for now we've removed the upfront loading/unpacking until we can find the root cause of the issue.
This should make the game boot up way faster for now. Thanks for the reports!
Boot time fix
Source: Steam Community (opens in a new tab)
Build and release context
Recorded Steam release date:
Within one calendar day of this post (UTC). The listed date does not establish an exact launch time.