No, the time for the mainthread is not normal. There is definitly something wrong. I use a 5600 and have 12ms in the main thread for the original scenario with the settings from the screenshots.
Perhaps the remains of a mod …?
(4k 60-65 FPS @ KMSF, 3080, 3200 RAM)
What about other software/games. Is the performance normal in other use cases?
The high manipulators value is not normal: Check you sound device: