How to check ARC (Avatar Rendering Cost) ? Advanced tab --> Rendering --> Info Displays --> Avatar Rendering Cost.
Mind ARC isn't doing everything, kicking my AO off leaves my ARC to 16.. so why would I need to take it off... Scripts ! The more scripted objects you have, the more lag it causes. So kick the prims away and kick the AO, radars, HUDs ... That'd be awesome.