When the graphics are on Fast in options the trees graphics are fancy and fast

The trees are weird and it lags the game so much I usually get 100 fps on mine now I get 13 because the graphics on options is fast while there is fancy trees etc if you dont understand I will show you a picture when Im close to the trees its fast, when im not its fancy and when I do get close to the fancy trees they turn fast which lags the game.
Here is a picture ---> http://prntscr.com/44bfx6