Found a major part of the problem, the tree itself. I played with the tree lab for a couple of hours, but finally got feed-up with how stupid most of the trees look. So, I downloaded Tree Generator 1.2 from Cnet. With TreeGen I was able to make a fairly-good tree. What makes it look so good is also a major part of the bottleneck, its got almost 40,000 polys. For those who wanted specs, I have an AMD K6II 500 with only 128Mb of RAM. Yes, I know, old.