I'm not sure what you mean when you say network applications that provide at least adequate performance. Aren't Java web-servers at the very top of every performance test? Isn't Java the #1 choice for low-latency high-frequency-trading applications? Aren't HBase, Hadoop and Storm running on the JVM?
The whole point of java.nio introduced over 10 years ago, back in Java 1.4, is robust zero-copy networking (with direct byte-buffers). Higher-level networking frameworks, like the very popular Netty, are based on NIO (although, truth be told, up until the last version of Netty, there was quite a bit of copying going on in there), and Netty is at the very top of high-performance networking frameworks in any language or environment.
The whole point of java.nio introduced over 10 years ago, back in Java 1.4, is robust zero-copy networking (with direct byte-buffers). Higher-level networking frameworks, like the very popular Netty, are based on NIO (although, truth be told, up until the last version of Netty, there was quite a bit of copying going on in there), and Netty is at the very top of high-performance networking frameworks in any language or environment.