Hard to say really.
no to spiking though as regards to the 'all out attack' on forums the other week, then I could imagine there was a strong possibility that some servers could have come under CPU pressure and may have caused some slow downs.
I havent noticed a spike in usage through it - the forum traffic is minor compared to the main site, so in the grand scheme of things its not made any difference to bandwidth
I also have a couple of lines of 'defence' some are logged - Those that are stopped at the first hurdle arent, but I should imagine if I could be bothered to go through the traffic logs (which Im not going to!) they will all originate from either beijing or eastern block type countries. Theres still some that are getting to stage 2 which are logged, as an indication theres been 16 of those in the past 12 hours which have been stopped and logged. I think you can gather from that, that I'm already using some pretty large IP blocks - which I maintain and add to myself.