Use one thread per core. Using more than one thread per core will actually slow it down due to the overhead to switch between the two threads. One exception is if you have several processes that are actively using processor time. For example, 3 other processes plus one thread for this, each process will get 25%. Set Terragen to two threads, and each process gets 20%, but Terragen will actually get 40% due to using 2 threads. This only applies if the other processes are not idle, i.e., each thread shows 20% processor usage all the time.
So, if you have a dual processor system using two Quad core processors, use 8.
If you still have the 1.2 GHz Celeron listed in your specs, use 1.
HTH
Jerry
