First of all welcome to the forum!! 
So it sounds like you’ve never gotten good performance from the 9950x3d/5090 with the sim? Was this PC ordered from a 3rd party retailer or did you build it?
I have a PC with a 9950x3d/7900xtx and I’m very happy with it’s performance.
You can see my 4k performance test results here.
Some additional performance tests in 1080p here.
I listed all of my settings with the second test and the only difference was the 1st test was in 4k and the 2nd test was in 1080p. I didn’t use any 3rd part software add-ons as those can sometimes inject poor performance. Your results should be better than mine with your 5090.