ServiceStack does not look so good here, some are slow, others are failing entirely. I would be particularly interested in nginx and smart thread pool results being updated
This is because Mono's HTTP Stack has load and stability issues, which is unlikely to be improved. The best shot for good performance of .NET on Linux in future is with Microsoft's CoreCLR which we'll look at porting to after it's released.
Until then you can look at the HttpBenchmarks Demo App which runs TechEmpower's benchmarks on different ServiceStack hosts on Windows: