Citrix users experience slow performance and freezing sessions

You could force these users to use a proxy script using a GPO.

The proxy script is a simple JavaScript, allowing you to direct connection through different proxies or direct.

Create the script so that allowed sites are sent DIRECT or through the proxy used on your network (if any), but any undefined sites are sent to a bogus proxy address.

It could be something like this:

var local_ip = myIpAddress();

function FindProxyForURL(url, host) 
{

    // Resolve host to IP address
    var resolved_ip = dnsResolve(host);


    // --- BEGIN ALLOWED DESTINATIONS ---

    // Hosts and domains
    if (localHostOrDomainIs(host,   "intranet")                     ||
        localHostOrDomainIs(host,   "servicedesk")                  ||
        localHostOrDomainIs(host,   "serverfault.com"))
    return "DIRECT";

    // IP addresses
    if ((resolved_ip == "10.11.12.13")  ||
        (resolved_ip == "60.61.62.63")  ||  
        (resolved_ip == "80.81.82.83")) 
    return "DIRECT";

    // IP ranges
    if (isInNet(resolved_ip,    "10.0.0.0", "255.0.0.0")    ||
        isInNet(resolved_ip,    "172.16.0.0",   "255.240.0.0")  ||
        isInNet(resolved_ip,    "192.168.0.0",  "255.255.0.0")  ||
        isInNet(resolved_ip,    "127.0.0.0",    "255.255.255.0"))
    return "DIRECT";

    // --- END ALLOWED DESTINATIONS ---

    // Default to bogus proxy server on same subnet as client!
    return "PROXY 10.10.10.10:9999";

    // --------------------------------------------------

}

Replace "DIRECT" with "PROXY ProxyIP:ProxyPort" if a proxy is used. Replace the bogus proxy "PROXY 10.10.10.10:9999" with an IP address on the same site as your Citrix servers, to keep the dead-end traffic on the LAN.

If you wish, you can add more sophisticated conditions, e.g. regex matching on either the "url" or "host" variable.

Test your own script with http://code.google.com/p/pactester/.

Put the script on an internal web server with a .pac extension and put the URL in the GPO. Make sure to add the .pac file extension to the web server's MIME type list as "text/javascript".

I have never used PAC files for this purpose, so you probably want to ensure that Internet Explorer doesn't somehow fallback on DIRECT, when it fails to use the bogus proxy server.

Just an idea.

Try this: launch the app seamlessly via RDP instead of Citrix.

1. Launch mstsc
2. Go to Options and browse to the Programs tab
3. Check the Start the following program on connection checkbox and enter the full path and working directory of the application or script you are launching
4. Click Connect and login.

Observer the behavior of the application. If you see the same behavior, it is almost 100% certain that the problem is in the application, and 100% certain that it is not Citrix-related.

I have seen other applications behave this way when no other windows are present in the session. If another window is open in the session when the application launches, the behavior doesn't present.