Check the first post: https://www.beamng.com/threads/0-10-discussion-feedback-bugs-reporting-thread-read-1-post.43985/ We found some stuff that could have reduced performance on lower-end machines. Wait for the hotfix.
before the update when load the vehicles menu , u have to wait for it and when u do it again u don`t have to wait ,after the update even u spawn on a map ,when the car loads,u have to wait and u have to wait every time when u load the vehicle menu