I started this week a zerosim with mutation rate fixed at 32x, maximum Point Mutations and Delta Mutations (so mutation speed can stabilize itself over time, since I'm still using an install that crashes if I change settings), costs only for DNA length, and instadeath for bots that are 10000 cycles old. I think that's the best starting settings to get a zerosim going. They started to multiply before the first 10000 cycles extinction.
At 3 million cycles they have developed an amusing cycle of moving a short distance, reproducing, then firing some shots. They are kinda amusing to watch.
One problem with the nuclear reactor settings is there are so many mutations the mutation history seems to cut off before 1400000 cycles. I'll have to keep more intermediate saves, I guess (automatic saving crashes too).