I haven't had a chance to investigate yet. In all of the tests that I have run since switching to bridge mode, which is 4-5, my download spees around 250 Mbps which is what I am supposed to get but that first direct test seems to indicate that I was getting faster speeds, perhaps due to Speedboost.
In the first mode I had a laptop directly plugged into one of the ports of the Hitron Gateway and it was still functionig as a modem+router. In the second test the path was going through a lot more of my internal networking as the Hitron was acting as a cable modem - then my Asus NT-R66U is the router and then it goes through my 24 port switch before hitting the PC. I will try connecting the laptop directly to one of the ports of the Gateway to see what speeds I get like that, this is directly connecting your PC to the net without a router so I don't think I want to do that for too long.
All of the network equipment is Gigabit, which is obvious since otherwise I wouldn't get better than 100Mbps, and the PC that the second test was run on is faster than the laptop.
My network cabling is (I believe) CAT-6. Moving to faster internet speeds like this could highlight any other bottlenecks in your LAN.
That being said I am able to do PC-PC transfers at rates much higher than 250 Mbps so I would doubt it is anything in the cabling or the switch.
But it is also possible that the first test was a bit of an anomaly.