[AE CS6] Motion Blur

Hi guys i have a problem with After Effects.When I record a scene in 200fps in hlae and make it .avi in VD then I import it to After Effects But when i try to render it in 29,97fps with motion blur it gets realy laggy like it's 20 fps.Also when i do the same in Sony Vegas it came out smooth and not like 20 fps.Can someone help me about this problem ?