Using the default config you get when you reset the router...
NAT, FW ON ca 20MB/S
NAT, FW OFF ca 28MB/S (Max speed if I connect my computer directly too)
Any ideas how to get a better speed with FW on? (The FW-rules are the default ones)
What's the MTU set to on your PC? Since most of the RBs only support 1500 (1524 for the L2MTU), you may be fragmenting if both ends of the link think they can do jumbo frames.
1500 MTU on my PC, running W7The product page does show a pretty substantial hit for the firewall and connection tracking: http://routerboard.com/RB450G but with reasonable frame sizes it should still be able to do it. What OS version are you running? (The tests are apparently for v5.x)