Loop with multiple HTTPWebRequest and JSON deserializer slow

Question

Problem

I have a C# application where I have around 40 to 50 different Asana Task ID's. I want details for each ID so what I do is make a request in a for loop for each ID. The data is in JSON format:

// For each result in the data.
foreach (var result in results["data"])
{
    // ID for each Asana task in the data.
    string id = (string)result["id"];

    // Deserialize the JSON data so we can use it with an object and its properties.
    deserialize.SetJsonData(requestAsana.getSingleAsanaTask(id));

    // Add data to the list.
    asanaDataList.Add(deserialize.Data);
} 

The SetJsonData method deserializes the JSON data:

    private AsanaRootData root = new AsanaRootData();
    public string jsonData;
    public string SetJsonData(string json)
    {
        this.jsonData = json;

        root = JsonConvert.DeserializeObject<AsanaRootData>(jsonData);         

        return json;
    }

And the getSingleAsanaTask method is the method doing requests to Asana with given ID:

public string getSingleAsanaTask(string taskID)
    {
        try
        {
            // Make a request variable with URL and ID.
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(taskURL + taskID);
            // Speed up requests.
            request.Proxy = null;

            // Encode authentication value.
            String encoded = Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1").GetBytes(auth));

            // Add authentication to header.
            request.Headers.Add("Authorization", "Basic " + encoded);

            // Response variable.
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();

            // Get the stream associated with the response.
            Stream receiveStream = response.GetResponseStream();

            // Pipes the stream to a higher level stream reader with the required encoding format. 
            StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8);

            return readStream.ReadToEnd();
        }
        catch (WebException e)
        {
            Debug.WriteLine("\nInvalid Asana task ID\n");
        }
        return "";
    }

Questions

Sometimes I can have more than 50 tasks I want to load, still it can take up to 20 seconds. Is there a way to increase performance, or am I perhaps doing it wrong?

• I can see that I am creating a new HTTPWebRequest variable for each request, does that matter?
• Could it be my deserializing method that slows everything down?

What have I tried?

• ServicePointManager.DefaultConnectionLimit = connectionLimit;

• req.Proxy = null;

• ServicePointManager.Expect100Continue = false;

• Threading for the setJsonData method.

• Stopwatch timer = new Stopwatch(); where the requests took around 40% of the time.

Narrowed down to

• The following line is taking half of the time: HttpWebResponse response = (HttpWebResponse)request.GetResponse();