[AndreT]

Incognito's plugin has no limit (theoretically), but the amount of objects it can hold actually depends on your server machine. Every object uses some memory since the objects are stored in dynamic memory. Although it does use all sorts of methods to speed up the search process, you could still get some issues when streaming hundreds of objects in a small area for around 500 players.

But no, being serious now, how much lag there will be (or if any at all) depends on the amount of objects, your machine and amount of players.