http server for static files (slow response from external ip)

[CnApTaK]

i'm trying to use node.js for this task
var static = require('node-static');
var file = new(static.Server)(__dirname+'/../public', { cache: 3600 });
require('http').createServer(function (request, response) {
request.addListener('end', function () {
file.serve(request, response);
});
}).listen(8080);
and with this code i have slow response time (downloading time).
if i make request to localhost, everything is fine and quick.
but when i open url from another pc in our netework.
many requests have bigger time... localhost = 10-20ms, external request = 200+ms
http://i42.fastpic.ru/big/2012/0817/92/e60f7242b5b9c9dc2428db4e00c98d92.jpg
you can see in this image top example is local request, and bottom - external.
this is not our network problem, because this static content is tested with apache server, and there is no difference between local and external requests