PC Offline SP races start out slow

Starting a single player race offline the game slows down and the in game timer also slows down. 

Online mode the game never slows down in pvp playlists. 

When it happens i change the upscaler or the shadows and lighting options to fix this problem but it comes back when I start a race. It's been happening since Volume 5 and now Volume 6. 

Played on Steam.