Good Job Alan, this is exactly right.
You can see that for 1 reactor you are getting 6000 generations a minute but between 5-10 reactors your combined generations is 10000. So I would suggest that 5 is pretty optimal for you. Although 3 is getting 9000 generations per minute total which is also pretty good.
You must have good hardware, I find if I keep increasing the reactors then at some point I get a pretty drastic slowdown.
This is good info because it lets you save some resources for other things and also dont need to work the computer hard unnecessarily