Steam Snow Storm Fps/2(sometimes Almost 3)

In TSW4 snow strom drops your FPS a little, like from 60(sunny weather) to 54(snow storm). In TSW5 snow storm divides your FPS in half, sometimes at some locations even divides almost on 3. Like from 60(sunny weather) to 30(snow storm), From 50(sunny weather) to 19(snow storm). Frankfurt Main from 38 FPS to 14 FPS. I can't say it's playable like this.