Used as intended, the Elgato Thunderbolt SSD is quite quick for a portable external storage drive. From the QuickBench speed benchmark, we saw write speeds up to 264MBps, and sequential read speeds up to 271MBps.

From the QuickBench small-file transfer test (using samples from 4kB to 1024kB), we saw average sequential read/write speeds of 139/140MBps.

In the random read/write test with same small files, performance was still very good at 127 and 139MBps respectively.

Do note the near-symmetrical speeds of read and write performance. This suggests that QuickBench is using compressible data in its data transfer calculations.

Unfortunately SanDisk Ultra 120 uses a SandForce controller, which accelerates write performance by pre-compressing incoming data. While this allows good performance from data that is compressible -- such as text files and spreadsheets -- it behaves much less well with already-compressed media files such as JPEG, MPEG and MP3 files.