将数据下载到app非常慢

Question

我写的是uwp app。

我尝试下载json并显示数据。

我发送方法lan和lon变量，把它和链接并下载数据。

位置代码：

 public class LocationManager
{
    public async static Task<Geoposition> GetPosition()
    {
        var accessStatus = await Geolocator.RequestAccessAsync();

        if (accessStatus != GeolocationAccessStatus.Allowed) throw new Exception();

        var geolocator = new Geolocator { DesiredAccuracyInMeters = 0 };

        var position = await geolocator.GetGeopositionAsync();

        return position;
    }
}

下载JSON代码：

     private const string APPID = "f3c45b5a19426de9ea6ba7eb6c6969d7";
        public async static Task<RootObject> GetWeather(double lat, double lon)
            {
                var http = new HttpClient();
                var url = String.Format(
                    "http://api.openweathermap.org/data/2.5/weather?lat={0}&lon={1}&units=metric&APPID="+APPID, lat, lon);
                var response = await http.GetAsync(url);
                var result = await response.Content.ReadAsStringAsync();
                var serializer = new DataContractJsonSerializer(typeof(RootObject));

                var ms = new MemoryStream(Encoding.UTF8.GetBytes(result));
                var data = (RootObject) serializer.ReadObject(ms);

                return data;
            }
        }

        [DataContract]
        public class Coord
        {
            [DataMember]
            public double lon { get; set; }

            [DataMember]
            public double lat { get; set; }
        }

        [DataContract]
        public class Weather
        {
            [DataMember]
            public int id { get; set; }

            [DataMember]
            public string main { get; set; }

            [DataMember]
            public string description { get; set; }

            [DataMember]
            public string icon { get; set; }
        }

        [DataContract]
        public class Main
        {
            [DataMember]
            public double temp { get; set; }

            [DataMember]
            public double pressure { get; set; }

            [DataMember]
            public double humidity { get; set; }

            [DataMember]
            public double temp_min { get; set; }

            [DataMember]
            public double temp_max { get; set; }
        }

        [DataContract]
        public class Wind
        {
            [DataMember]
            public double speed { get; set; }

            [DataMember]
            public double deg { get; set; }
        }

        /*
        [DataContract]
        public class Rain
        {
            [DataMember]
            public double __invalid_name__1h { get; set; }
        }
        */

        [DataContract]
        public class Clouds
        {
            [DataMember]
            public int all { get; set; }
        }

        [DataContract]
        public class Sys
        {

            [DataMember]
            public int type { get; set; }

            [DataMember]
            public int id { get; set; }

            [DataMember]
            public double message { get; set; }

            [DataMember]
            public string country { get; set; }

            [DataMember]
            public int sunrise { get; set; }

            [DataMember]
            public int sunset { get; set; }
        }

        [DataContract]
        public class RootObject
        {
            [DataMember]
            public Coord coord { get; set; }

            [DataMember]
            public List<Weather> weather { get; set; }

            [DataMember]
            public string @base { get; set; }

            [DataMember]
            public Main main { get; set; }

            [DataMember]
            public Wind wind { get; set; }

/*
                                                [DataMember]
                                                public Rain rain { get; set; }
                                                */

            [DataMember]
            public Clouds clouds { get; set; }

            [DataMember]
            public int dt { get; set; }

            [DataMember]
            public Sys sys { get; set; }

            [DataMember]
            public int id { get; set; }

            [DataMember]
            public string name { get; set; }

            [DataMember]
            public int cod { get; set; }
        }

在那里我显示这样的数据：

 public async void WeatherDisplay()
    {
        try
        {
            //var position = await LocationManager.GetPosition();
            var geoLocator = new Geolocator();
            geoLocator.DesiredAccuracy = PositionAccuracy.High;
            Geoposition pos = await geoLocator.GetGeopositionAsync();
            var lat = pos.Coordinate.Point.Position.Latitude;
            var lon = pos.Coordinate.Point.Position.Longitude;

            RootObject myWeather =
                await OpenWeatherMapProxy.GetWeather(
                    lat,
                    lon);



            Temperature.Text = ((int)myWeather.main.temp).ToString() + "°C";
           // DescriptionTextBlock.Text = myWeather.weather[0].description;
            City.Text = myWeather.name;
        }
        catch
        {

        }
    }

我遇到延误问题，点按按钮，它会在30-40秒内显示数据。随着互联网一切都好。为什么我有这么大的延误？