Macworld Lab recently . In response to that report, readers want to see how Thunderbolt speed stacks up against other interface technologies--specifically, eSATA.

As with the Thunderbolt/FireWire 800 tests, we still have an issue of coming up with similar external devices. The has six drives and only one type of connection: Thunderbolt. We don't have access to a six-bay array with eSATA, so for comparison, we used the Promise , but it has four drive bays and FireWire 800, USB 2.0 and eSATA ports. With both external arrays formatted as RAID 0, we found the Thunderbolt performance to be nearly four-and-a-half times faster than eSATA in our AJA System Test read results, and about eight times faster than eSATA in our AJA System Test write results.

With our 2GB file tests, we copy a 2GB file from the Mac's internal drive to the external array, which tests the write speed of the external array. Then we copy the 2GB file back to the internal, which tests the external's read speed. We repeat the tests with a folder containing 2GB worth of files.

At first, these tests showed different results compared to the AJA System Tests--the eSATA results were very similar to the Thunderbolt results, and FireWire 800 even put up decent numbers. The problem was the slow internal drive in the MacBook Pro, so we pulled the SSD out of the 15-inch MacBook Pro and installed it into the 17-inch MacBook Pro. The bottleneck was removed, and we again saw large performance differences between the three interfaces.

When reading a 2GB file, Thunderbolt was 39 percent faster than eSATA and twice as fast as FireWire 800. Writing that 2GB file, Thunderbolt was over two times faster than eSATA and 2.8 times faster than FireWire 800. Reading a 2GB folder, Thunderbolt was 30 percent faster than eSATA and 73 percent faster than FireWire 800. Writing the folder, Thunderbolt was two times faster than eSATA and 2.4 times faster than FireWire 800.