As noted by the developer, “We’ve submitted our update to Sony to resolve performance issues affecting some within Far Harbor.
Far Harbor has been out since May 19th and complaints of its PS4 performance have been pretty consistent since then.
After reports came out of Fallout 4’s Far Harbor running rather terribly on the PlayStation 4, Bethesda Softworks announced on Twitter that it had submitted an update to Sony to fix the same.
Performance on the Xbox One was also problematic but noted to be better than the PS4 version.