Currently (as of 66830 to be precise) area patrols on a planetary scale by mid->large numbers of units causes drastic degradation of server and sim fps. Land units seem to be the most effective for recreating this. The last time I replicated this, I had just established a teleporter on a new planet and started flooding units through. As I didn't know for certain if the planet was occupied I set the units to patrol the planet as a lazy scout. In this case I believe there was ~50-60 units that I gave that order to. After I gave that order the server's fps went from ~30 -> ~12 and the sim dropped from 10 to ~6. While this is not a crippling situation, it does cause a noticeable enough effect that I not avoid giving these orders. I believe this was while fighting the Revenant leader in GW, so all planets in the system were small moons. While I don't believe this is a particularly high priority to fix, I do want to make sure you guys (Uber) are aware of this. Random Guessing (Sorry, force of habit; if I find something wrong I have to guess): As this is most affected by land units, I suspect it occurs due to the overhead of pathfinding for all of the movement commands this would cause. Off the top of my head, I would guess that each time a unit under an area patrol makes a change in direction the pathfinding is called twice in quick succession; once for validating the target location (or making it) and then again for getting the unit to move. Actually scratch that... it's likely two different algorithms, but I would guess the creation of the 'move target' would be the greater processing load.
