Node.js RSS much higher than Heap

Question

Just a simple question about Node.js memory usage. Is it normal for Node? Take a look at this:

{ rss: 788246528,
  heapTotal: 110231552,
  heapUsed: 67313680,
  external: 90448493 }

I'm using socket.io lib, Total socket.io clients: 2378 When I start the node process - RSS is about 200MB, then rises to 800MB and keeps stable, so there are no any memory leaks in my code. Is it normal? I understand that V8 needs memory but how much? Using similar server developed in Java and it takes much less memory (about 200MB).

Thank you.