Ok, here is what I heard somewhere, tested it and it works. How to use multicore processors to speed up darwinbots. Don't know if it was written here, but maybe it's good to repeat
In my case, I have dual core AMD turion processor. I started two simulations simultaneously. Then open task manager. Find processes Darwin 2.44.04.exe (depending on the version You are using, right click and click "set affinity" then You can assing each sim to one core. If You have more cores you can start more sims. You can connect them with teleporters to form one big sim and so on... Hope that this will help a little...