Utilities 15 - System Optimize

I've been using Utilities 15 for some time now but haven't been able to understand just what is happening when using optimize with the Processes icon highlited. The Norton onlne help file gives just brief note but doesn't explain this part of optimize process well. Does anyone know specifically what Utilities is doing to computer programs while in this mode? I can see specific programs highlighted in the listed items at different times which I guess means they a running but what's being  done to them if anything?