Thanks to all)
So, I was tryed Onyx Tree... I can say, that its generate trees with about 100-150K polygons on each. And there is 'minimize' function, that reduce number of polygons to 20-40K
I was launch SU with imported model, and it start to work very slow (AMD 5200+, not the best for the 3D, but...)
I'm working with landscape modelling, and I need realistic trees very much
So, what should I do? Maybe settling in 3Dsmax?
Or I have to try SU with imported tree on quad-core processor? Will it help?