ARC denotes Avatar Render Cost. We have had this tool in the viewer for some time. When used we see a numeric value that is green, yellow, or red. Red denotes the avatar’s render cost is too high… according to someone. It tells me I’m almost dressed…
You can enable ARC reporting in Viewer 2 and 3 via the top menu. It is in the Advanced item. If you do not have an Advanced item in your menu press Ctrl-Alt-D (viewer 3 is a little strange, if you have a problem try using ‘D’ or ‘Q’ with Ctrl-Alt to get Advanced open). Then in V2: Advanced->Rendering->Info Displays->Avatar Rendering Cost. Or in V3 use: Advanced->Performance Tools->Show Draw Weight for Avatars. The change from old ARC numbers to new Draw Weight numbers is about 10 times greater.