Node + SSL = SLOW

I have set up a node.js-server for running a chat service used by our site. It works. However some customers are NOT able to connect (is done automatically via javascript). They never pop up in the list of connected users (in ie 7,8,9).

My site is running on https (port 443) and therefore my node.js-server is also running on SSL (port 8443) (with the same certificate).

I am using Node 0.6.20 (have tried numerous other versions). I have the following package-setup:

{
    "name":"My Chat",
    "description":"Chat app using socket.io",
    "version":"0.0.1",
    "dependencies":{
        "express":"3.x.x",
        "socket.io":"~0.8.7"
        },
    "engines":{"node":"0.6.20"}
}

and my node server looks like this:

var fs = require('fs');
var express = require('express');
var https = require('https');
var sio = require('socket.io');

var https_options = {
    pfx: fs.readFileSync('cert/certificate.pfx'),
    passphrase: "password"
};
var PORT = 8443;
var HOST = '0.0.0.0';


var myArray = new Object();
var userArray = {};
var nicknames = {};

app = express();

    app.use(app.router);

server = https.createServer(https_options, app).listen(PORT, HOST);
console.log('HTTPS Server listening on %s:%s', HOST, PORT);


var io = sio.listen(server);

io.set("transports", [ 'websocket'
   , 'flashsocket'
   , 'htmlfile'
   , 'polling'
   , 'xhr-polling'
   , 'jsonp-polling']);


// routes
app.get('/hey', function(req, res) {
    res.send('HEY!');
});
app.post('/ho', function(req, res) {
    res.send('HO!');
});

io.sockets.on('connection', function (socket) {


});