She should finish the year. She can start working on transfer applications, and transfer for the fall. Sometimes students find their footing second semester, though. I think a student pulling a 3.9 at a top tier university may not be doing anything but studying, which could contribute to her social isolation. I personally would rather that my kid had slightly lower grades and maybe joined a couple of clubs or activities. You should tell her this. Both my kids had lousy freshman roommates, too, and one switched to a different room at winter break.
It is too late now to second guess whether she could have made a better choice. I always think overnights at accepted student days are a good idea. But I would walk a line now of both supporting transfer apps, but also finishing out her year and trying to engage more in campus life during the second part of the year.