HttpClient client = new HttpClient();

using (Stream s = client.GetStreamAsync("http://www.test.com/large.json").Result)
using (StreamReader sr = new StreamReader(s))
using (JsonReader reader = new JsonTextReader(sr))
{
    JsonSerializer serializer = new JsonSerializer();

    // read the json from a stream
    // json size doesn't matter because only a small piece is read at a time from the HTTP request
    Person p = serializer.Deserialize<Person>(reader);
}