Scan performance is highly dependent upon the network conditions during the time of the scan. The QualysGuard scan engine will throttle performance settings based on network conditions.
That being said, this thread likely has the information that you're looking for, this document has a little information on bandwidth utilization, here are some statistics on pps that we've seen in the wild, and of course, you should review our document on scanning through firewalls.
Hope this helps,
I had thought someone said 30-35 per second if you have four cores. Which woul140.d mean in two seconds you could scan 60, in 120 seconds you could scan .