I measured the HPACK compression ratio of Traffic Server 6.1.1 (+TS-4092) with hpack-test-cases. http://paste.apache.org/0uY6
It looks the result is good enough. There are few things we can do for compression ratio, but I think it would be better to focus on improving performance. I'm going to create a ticket about how we can take the test cases into our tests, because they are external resource. https://github.com/http2jp/hpack-test-case https://github.com/http2jp/hpack-test-case/wiki/Compression-Ratio
