The Apple Thunderbolt Display has a Gigabit Ethernet port.
I just plugged in my Ethernet cable to the back of the monitor, and ran a speedtest, whoa!
Thunderbolt Display: Ping = 8ms
Download Speed = 34.60 Mbps
Upload Speed = 5.03 Mbps
I'm in the top 9%. ;-)
How fast is your internet connection?
Is there anything that you do to make it faster?