Add me to the list of those affected by these performance issues. Took a short break from the sim at 2.9.5.55918, then came back a few days ago only to realize DCS became unplayable for me if I want to run a complex mission.
In 2.9.5 my fps/frametime graph would show a flat line, keep the frames at 100+, and I could run these heavy missions from start to finish without a single stutter. Now it's filled with steps and spikes, and seems to get worse as soon as more AI units are being spawned, and also deteriorates the longer the mission runs (to the point of single digit fps).
Attached is the log from a quick test session I just did using the last mission of the FIWOS campaign. I also have the track file but it's the whole flight that I've recorded, and exceeds the attachment upload limits
dcs.log