[tor-relays] tuning MaxAdvertisedBandwidth for CPU

i've got an exit node that is doing a fair bit of bandwidth, but I think it is CPU bound at this point because I am getting these:

Your computer is too slow to handle this many circuit creation requests! Please consider using the MaxAdvertisedBandwidth config option

i'm wondering what I should set the MaxAdvertisedBandwidth to if I am averaging this type of traffic: http://torstatus.blutmagie.de/router_detail.php?FP=131b60b9afe6aea60042132d6...

it seems from the graphs, there are some clear plateaus at around 5100000, but I figured that folks here might have some suggestions that are better than just setting MaxAdvertisedBandwidth just to that number

thanks! micah