Common comments: Current implementation of encryption support leads to performance drop from 1.28 till 2.36 times depending on operations (for bricks formatted with ext4). The most affected operation is reading a largefile. The least affected operation is creating a large set of small files.
Looked at another way, performance with encryption is 42-78% of performance without. That actually doesn't seem too bad, considering that some people need encryption regardless of the cost. Consider people who use Tahoe-LAFS, for example, despite the fact that it has absolutely *atrocious* performance characteristics. It would be interesting to see how these numbers scale up with more concurrent application threads, or as clients/servers are added. Since you don't mention a network type, am I correct in assuming that these numbers were all from client and server processes together on a single machine?