Wind Zone didnt work for model from SpeedTree

Just exported model from SpeedTree to Unity with wind
Added WindZone to terrain, but wind doesnt work(It works very very very slow, i cant even see that)
And after some time its going little faster and fasterwith a time
What s the problem?

ANd i think i know why
I havent got this[117874-екуууу.png|117874]