Faster file lookup

I’m polling an ashx handler to check if a specific file is present and return true or false depending on it.

public void ProcessRequest(HttpContext context)
{
    int myId;
    if (context.IsRequestClean())
    {
        if (int.TryParse(context.Request["id"], out myId))
        {
            var directory = Directory.GetDirectories(context.Server.MapPath("~/App_Data/Files"), "*" + myId, SearchOption.TopDirectoryOnly);
            if (directory.Length > 0)
            {
                if (Convert.ToInt32(directory[0][directory[0].Length - 1].ToString()) == myId)
                {
                    context.Response.ContentType = "text/plain";
                    context.Response.Write("true");
                }
            }
        }
    }
}

How can I speed the above up?

If you want a shorter time between file is created until the client is notified, I recomment you implement long-running queries, for example using SignalR.

Then setup a FileSystemWatcher that notifies the query as soon as the file is present.