[nodejs] how to speedup http-proxy performance

Dear all

i'm experiencing some performance-gap using http-proxy.

I've got a very simple server that does the following:

var http = require('http');
var httpProxy = require('http-proxy');
var proxy = httpProxy.createProxyServer({});


var server = http.createServer(function(req, res) {
    proxy.web(req, res, {
        target : 'http://127.0.0.1:19007'
    });
});

server.listen(19081);


if i test my server with:

ab -c 100 -n 10000
http://foo:19081/data/_8d51df079d51bc090dc2307310b474fc_CONTENT

i have:
Requests per second: 553.79 [#/sec] (mean)
Time per request: 180.575 [ms] (mean)
Time per request: 1.806 [ms] (mean, across all concurrent requests)
Transfer rate: 36467.65 [Kbytes/sec] received


but if try to go directly to the port 19007 (served by apache):

ab -c 100 -n 10000
http://foo:19007/data/_8d51df079d51bc090dc2307310b474fc_CONTENT

i have:
Requests per second: 1713.75 [#/sec] (mean)
Time per request: 58.352 [ms] (mean)
Time per request: 0.584 [ms] (mean, across all concurrent requests)
Transfer rate: 112853.17 [Kbytes/sec] received

i've tried also to enable cluster and fork some more process in the nodejs
script but i'm not able to take over ~700 req/sec.

Can you help me to figure it out ?

- is a problem of implementation of my simple proxy ?
- is a "normal" gap ?
- maybe http-proxy has too many features and in this scenario i need
something lighter and faster ?

Thanks to all in advance