Github repo currently has Netty.IO at 4.1.16; the 5.x series has 4.1.13. There appear to be a number of bugfixes that might be helpful for performance reasons. They've also beefed up their HTTP/2 support considerably: which I'm not sure would be useful here, but may be?
http://netty.io/news/2018/05/14/4-1-25-Final.html
Github repo currently has Netty.IO at 4.1.16; the 5.x series has 4.1.13. There appear to be a number of bugfixes that might be helpful for performance reasons. They've also beefed up their HTTP/2 support considerably: which I'm not sure would be useful here, but may be?
http://netty.io/news/2018/05/14/4-1-25-Final.html