It's not actually a bug fix that has caused the problem. The stuttering is apparently caused by the developers' attempt to do something about the FSS delay in scanning for planetary surface features, which is related to the way in which planet surfaces are procedurally-generated. I think. I'm not a developer.
Indeed. The developers broke the cardinal rule of beta testing: "only fix bugs, don't add new functionality". And then they didn't do a second round of beta testing to see if there were any widespread issues introduced by the fixes done to fix the bugs found during the first beta test. I hope this is a lesson that they take to heart: whenever you make drastic changes to functionality, do a large scale alpha test and only fix bugs found. Then do a beta test to find the bugs introduced by the fixes for bugs found in the alpha test and finally do a gamma test for the fixes for bugs found in the beta test. NEVER introduce new functionality after the alpha test phase, or if you do start a new alpha test!