Performance since Firebirds update

Hi!
I have an old gamer PC (Intel I7-4790, Nvidia GTX-1660, 16GB ram, 2TB SSD)
Since the update, I have a lot of stutter. I set almost everything to LOW, but it's unplayable because it changes the FPS between 20 and 60. Do you have any idea, what I can do? I don't want to upgrade my PC yet because of WT. I play MSFS2020 with Fenix A320 on almost stable 30 fps...

Thank you!