The stuttering is really bad for me as well, i can't seem to have an enjoyable experience with DCS since the last few updates even with my specs - 13900KF, 64gb Rams, 4090, 2TB M.2. Hopefully it's resolve soon, BUZZ KILL...
I am having the same issues with this training mission, everything goes well until the last- manual reversion. To me it seems like a bug because same was reproduced outside the campaign, with a single player mission where I had to perform a landing and no issues landing (not a simple task). The plane spirals out of control and i was very gentle on the stick and trims.