@kingfish found that Windows has a major bug with Forza 5 and a few other games: https://community.amd.com/t5/general-discussions/use-windows-game-mode-while-gaming-on-your-windows-...
Disable Windows Game Mode in Windows Settings and see if Forza 5 works that way it should. Microsoft says they are working on a fix for it.
Nah, still the same
For cars increase world car lod, for crowd havent found soulution.
2 driver updates and 1 game update, everything still the same
I’ve been an avid horizon player since 2012 and I can say with confidence that fh5 is the buggiest launch they’ve had. These issues will eventually be buffed out, as they usually are. At least they aren’t wiping peoples data like in fh4.