Performanceprobleme ListView Bilder

public class FillList extends AsyncTask<String, String, String> {
        String z = "";


        List<Map<String, String>> prolist = new ArrayList<Map<String, String>>();


        @Override
        protected void onPostExecute(String r) {


            String[] from = {"A", "B", "C", "D"};
            int[] views = {R.id.Platzierung, R.id.Name, R.id.profilbild, R.id.Anzahl};
            final SimpleAdapter ADA = new SimpleAdapter(getActivity(),
                    prolist, R.layout.lsttemplate, from,
                    views);
            lstpro.setAdapter(ADA);


        }


        @Override
        protected String doInBackground(String... params) {


            try {
                Connection con = connectionClass.CONN();
                if (con == null) {
                    z = "Error in connection with SQL server";
                } else {
                    String query = "Select Count(ID) as Anzahl, Name from scan Group by Name Order by Anzahl Desc ";
                    PreparedStatement ps = con.prepareStatement(query);
                    ResultSet rs = ps.executeQuery();


                    int i = 1;
                    while (rs.next()) {
                        Map<String, String> datanum = new HashMap<String, String>();
                        datanum.put("A", i + ".");
                        datanum.put("B", rs.getString("Name"));
						//Bildernamen haben denselben Namen, wie die abgefragten Namen ==> den Personen die Profilbilder zuordnen: 
                        datanum.put("C", String.valueOf(getResources().getIdentifier(rs.getString("Name").toLowerCase(), "drawable", getActivity().getPackageName())));
                        datanum.put("D", rs.getString("Anzahl"));


                        prolist.add(datanum);


                        i = i + 1;
                    }




                    z = "Success";
                }
            } catch (Exception ex) {
                z = "Error retrieving data from table";


            }
            return z;
        }
    }