When asked about this on Twitter, CD Projekt Red Community Co-ordinator Marcin Momot confirmed that the day one update for The Witcher 3 will include frame-rate and performance fixes:
@DavidMo92898701 yes. Framerate and performance have already been improved.
— Marcin Momot (@Marcin360) May 12, 2015
Asked a similar question about frame-rate improvements coming day one, he replied, “Yes. We’ve already addressed this issue. Frame-rate will be better once we official launch the game.”
As well, if you’re hoping to download The Witcher 3 file early on PS4, Momot confirmed that the pre-load should start later today:
It should be coming to select territories (US, most of Europe, including Poland) later today.
According to the PlayStation Store, it will be a 35GB download.