Tyler Hicks wrote with the code, "Improve performance when AES-NI (and most likely other crypto accelerators) is available by moving to the ablkcipher crypto API. The improvement is more apparent on faster storage devices. There's no noticeable change when hardware crypto is not available."
The AES-NI (Advanced Encryption Standard New Instructions) instruction set extension is supported by modern Sandy Bridge and Ivy Bridge CPUs (along with some Westmere CPUs) on the Intel side while AMD Bulldozer CPUs and newer also implement AES-NI. This instruction set extension improves encryption and decryption performance.
Previously I have delivered AES-NI disk encryption benchmarks but now with the Linux 3.10 kernel when using eCryptfs it should be even faster. I continue to recommend using full-disk Linux encryption for all portable, production laptops.