Are you sure this fan behaviour is a regression from 3.09? I posted about a year ago about the slow ramp up time of the fan and your graphs in the GitHub issue look very similar to what I observed. There was also a response by Kieran that shed a bit more light into the issue, which appears to stem from where the driving thermal sensors is, and hinted towards a potential workaround coming up as a backport from the FW16 (not sure how far this has progressed).
I upgraded from 3.05 to 3.09 a couple of weeks back and have had no issues or observed any regression so far, incl. fan behaviour.