This has been reported on the forums often over the last few months and isn’t specific to recent NVIDIA or MSFS updates; the Los Angeles area has a huge amount of photogrammetry detail spanning maybe a hundred miles from end to end (hence a lot of data loading as you traverse the area, causing stutters) and a lot of airports (and thus both live or AI traffic and multiplayer traffic that slow down CPU main thread). So this is not super surprising given that these things are known to slow down the sim.