TB1 and TB2 might not have had enough bandwidth for high-performance stuff but it did have more than enough bandwidth to blow IGPs out of the water: DYI external TB2 systems had 80~90% of "internal" desktop performances on synthetic benchmarks[0], even with a TB — EC chain you could reach very, very respectable performances[1]

[0] http://www.anandtech.com/show/7987/running-an-nvidia-gtx-780...

[1] http://forum.techinferno.com/implementation-guides-apple/427...