Saving away URL query parameters in an analytics application

We are trying to use NodeJS for analytics. The following code gets the parameter from a URL and dumps it into a flat file. Is there any way to optimize it to get better response time?

var http = require("http");
var url = require("url");
var cluster = require('cluster');
var fs = require('fs');
var numCPUs = require('os').cpus().length;
var stream = [];
if (cluster.isMaster) {
        for (var i = 0; i < numCPUs; i++) {
                cluster.fork();

        }
        cluster.on('death', function(worker) {
                console.log('worker ' + worker.pid + ' died');
        });
}
else{
    var server = http.createServer(function(request, response) {
        response.end();
    });
    stream = fs.createWriteStream("nodejsCluster"+cluster.worker.id+".txt");
    stream.once('open', function(fd) {
        server.listen(8084);
    });
    server.on('request', function(request, response){
            var parsedUrl = url.parse(request.url, true, true);
            var queryAsObject = parsedUrl.query;
            stream.write( ( new Date()  )+'This is the content to write into file '+queryAsObject.test+"\n");
    });
    console.log("Server is listening"+cluster.worker.id);
}