What SDK version are you using? Are you using the latest AMSDK 7.0, or 6.0? The crypto drivers underwent some change between these versions, so it will be useful to know what version you have, especially if it is the latest version.
Can you explain what your IPSec software stack looks like? What kernel modules have you added (if any)?
Lots of issues can contribute to low performance using the crypto hardware, ranging from your packet size to encryption algorithm used could make a difference.
Once we understand what your system is, we can probably give some suggestions.