I have run a bunch of tests for the new durability options and there are three things I notice...
These tests were run with 4 node CB cluster, 4 client machines with 25 threads on each client machine executing YCSB workload A, and SDK 3.0 with new durability options.
1: All new durability levels have exactly the same throughput.
2: All new durability levels severely underperform the analogous old durability options.
3: The performance is not impacted by the SDK.
I have been working with Michael Nitschinger to eliminate the possibility that the SDK is causing performance issues. It seems like we can rule out the SDK being the cause. From the observations it looks like the new durability options have a different code path than the old durability options and that this new pathway has a single threaded bottleneck somewhere.