I hope this helps: i noticed that when i display sl in a window (say 640 x 480) and the SL window is active (say I click on it or write in chat) the CPU goes 100%, no matter if im looking at a complex 3d scene or at the script editor.
just clicking outside the window (i mean that all 3d pipeline continues to update the window) the CPU goes 30% - 40%. Since i'm crashing every 2- 5 minutes from weeks and now i'm online for nearly two hours simply without interacting with the viewer, i guess that maybe you could consider this strange behavior.
I also add that i tried a couple of different videocards without any advantage, i tried to go minimum details, disabled all graphic features but still when i just click the viewer window my CPU is fully consumed by SL process. I'm sorry if this is not the right place to post this, but i just wish to be able to live more than 45 seconds for session.