Improve performance of ENCRYPT protocol

A stress tests with the following setup showed that performance (reads and writes/sec) is halved when ENCRYPT protocol is enabled:
Infinispan had distributed sync cache with 2 owners on 4 nodes, no transactions. The stress test used 10 threads on each node accessing 1024 byte entries, no conflicts on keys, 20 % writes, 80 % reads.

It would be great if we could improve the performance of ENCRYPT protocol.