recently I design garden and I collect many model from Google warehouse
when I add model "bush", my file become bigger (about 64Mb). and every time I move my view angle, it become very slow, and sometimes occur Hang

is this some kind of bug, or what?
if the bush is the problem, is there any other kind or the model as that bush?

I need that kind of bush


http://www.4shared.com/file/_9P82hsY/2_online.html
the bush name on files is "untitled"

thanks a lot