Sometimes I get "in a mood" when I'm at a live music event that is real laggy and I will turn on Avatar Rendering Cost and mute everyone who's ARC is over 2000.
The cost of rendering an avater that isn't being rendered is - rather obviously - 0. If you're camming over to people who weren't on your screen before and going "ahah! this one is responsible! *mute*" that's just plain silly. They weren't "costing" you a thing since they were off screen.
Position your camera at a point and angle that lets you see what you want to see (just moving the camera to a different spot can make an immense difference already) and then deal with avies that are actually being rendered if you're still having trouble (turn off particles, reduce the number of avies that are rendered in the debug settings, turn on avatar imposters and start dragging the avatar detail slider to the left).
It'll not only give better results, it looks more visually appealing as well since a bunch of gray dancing sprites on your screen isn't terribly nice either
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