node.js serving content slowly, but then randomly go back to fast

The situation is simple. I'm testing a simple node.js server but my browsers says it takes ~200ms to receive the content (wich is far too long, considering my server is local). The code:

var http = require('http');


http.createServer(function(request, response) {

    console.log('>> '+request.url);

    response.writeHead(200, {'Content-Type': 'text/plain'});
    response.write('just no! because no!');
    response.end();

}).listen(80);


console.log('server running at port 80');

I run it in ubuntu with the command sudo node test.js.

As you can see, the response is very tiny. But then, sometimes when I change the response it randomly chooses to go back to fast and takes ~9ms or so. I tested in chrome's inspect element and in firefox's firebug. I couldn't find a pattern at all, nor an explanation. What's happening, folks? thanks (: