I just released a new version of FractalTreesX . It's a total alpha, complete with loads of bugs and some very odd behaviour when the size of the tree changes, but it's a LOT faster. I think it's probably about 3-4 orders of magnitude faster now. And the code is completely rewritten and I am MUCH happier about that. I would even say go and read it, because it's pretty good looking. I removed the total spaghetti that someone (initials are MYI...) told me was a good way to do it and replaced it with a nice simple multithreaded engine.