How many Kinematic rigidbodies(2D) can i have in a device game without any lag ?

There is no answer -- depends on the exact device, how many are active at once, how close they are together, what else is happening.

But I think, in a test I did, 500 balls bouncing in a small space on an iPad3 was noticably slow. Think I recall that one or two hundred was O$$anonymous$$. And this was purposely making them collide a lot.

thanks. my main question was the second : do kinematic rigidbodies make cpu busy just like non$$anonymous$$inematics or not ?

and it seems that the answer is : no ! but i want to know exactly : how much cpu usage a kinematic 2drigigvody wants relative to a non$$anonymous$$inematic.