为什么图像从服务器json formate接收速度慢？

Question

这里我以json的形式从json接收一些图片并在listview中显示该图片，但问题是图像接收平滑慢，意味着显示1 pic和3,4秒后再显示一个和simillarly。 我想图片应该显示atonce，那么sholud我做什么？这是一些代码

 protected void onPostExecute(String result){
            String s = result.trim();



            loadingDialog.dismiss();

                JSONObject respObject;
                try {
                    respObject = new JSONObject(s);
                    String active = respObject.getString("status_message");


                    if(active.equalsIgnoreCase("success")){
                         JSONArray array = respObject.getJSONArray("response");
                            for (int i =0; i<array.length();i++){

                         JSONObject jsonObject = array.getJSONObject(i);
                         String icon= jsonObject.getString("image");
                         String name = jsonObject.getString("title");
                         String date = jsonObject.getString("date");
                          id = jsonObject.getString("id");
                          platformno = jsonObject.getString("platform");

                         //this is for integer datatype receving
                         // id = jsonObject.getInt("id");
                          //platformno = jsonObject.getInt("platform");




                          listitem.add(new Latest_list(icon,name,date,id,platformno));

                        }
                         lv.setAdapter(new Latest_customAdpater(LatestNews.this, listitem));    

                    }else {
                        Toast.makeText(LatestNews.this, "services received Fail", Toast.LENGTH_LONG).show();

                    }

                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

这是自定义适配器代码

 holder.icon=(ImageView)convertView.findViewById(R.id.NewsIconID);
        holder.name=(TextView) convertView.findViewById(R.id.txt_newsNameID);
        holder.date=(TextView) convertView.findViewById(R.id.txt_newsDateID);
        holder.id= (TextView) convertView.findViewById(R.id.txt_hiddenID);
        holder.platform=(TextView) convertView.findViewById(R.id.txt_hidden2);
        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }
        Latest_list services=newslist.get(position);
        Picasso.with(context).load(services.getNews_icon()).into(holder.icon);
        Log.d("Url",services.getNews_icon());
        holder.name.setText(services.getNews_name());
        holder.date.setText(services.getNews_date());
        holder.id.setText(services.getNews_id());
        holder.platform.setText(services.getNews_platform());