Although I'm using P3d V4, and did this while using Active Sky Cloud Art, I remember that I had something like this years ago with FSX.
Now, I'm not badmouthing Nvidia. I know that they're the absolute best video cards for games.
But I've read over and over that high resolution clouds slow them down. A lot. That may no longer be a problem. I don't know.
If you have Nvidia, give it a try. Maybe they've fixed the problem.
I'm using an AMD Radeon RX480 card, and this setting hasn't dropped any FPS.
If you like what you see, and I certainly do, you may want to give it a try.
Now THIS is what I call clouds!