The last time I compared performance between 'nearby local lights' and 'sun and moon only', I was pleased to notice that the speed difference was practically unmeasurable, even with lots of lights scattered around in-view. That was somewhere around 1.9.1.27.
Now with 1.10.0.30, I'm seeing somewhere between 20-40% slowdown with local lights enabled - to add insult to injury, this is even when there are no obvious lights visible and no visible difference between the results of the two options.
FX5200.