I use windows 7 with mc 48. I seem to be having an issue where having lot's of rovers will cause them to freeze up and delay on following orders. Another weird thing is that I deleted every single one of them and then made ten new adv builder bots and they still wouldn't go where I told them to go. I checked my task manager and cpu and RAM are fine, so this must be a software glitch or something. Either way, it's hindering my game progress greatly, and now the rovers won't move at all.
When I have multiple differen't types of rovers harvesting and building in the game, they seem to move to a resource node, stay there for five minutes, and then move back and stay at the drop off site for a time. I read where bast said that he put rovers on a differen't thread, but that only means that the only thing that that thread has to manage is rover pathing, which for less that 100 rovers, should work just fine. I probably had a max of 50 rovers on the map before I destroyed them all as a test.