autorun freezes the game until the motion or certain event is completed. so, use parallel process. parallel process is basically autorun, but without freezing and you can a lot of parallel processes at the same time. Too many create lag tho, fyi.
just set up the event with an image, and in its movement commands, make it custom and you can edit its move route. If you want it to loop, just make the path the event takes loop back to the first position it started in, and also there's a setting for looping inside of the movement tab, it's a little check box in the lower left corner when you're editing the movements.