We haven't seen this at all. We moved from a pair of unbonded T-1's to 10 M/bps fiber on R55 & a Nokia IP530. When we tested the raw line throughput before the cutover using a file transfer in the ISP's data center as well as
http://www.speakeasy.net/speedtest, we got very close to the 10 M/bps speed. That was using a laptop with a personal firewall.
Once we made the cutover to the IP30 it was still the same.
We did have issues with auto-sensing on the NICs, though. We forced everything to 100 M/bps and all was well. Auto-sense caused a lot of speed issues.
I've got just about every SmartDefense setting running as well.FWIW,
Ray