Android - Getting list of installed apps takes too long

Question

First attempt:

    Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
    mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);            
    Intent pickIntent = new Intent(Intent.ACTION_PICK_ACTIVITY);
    pickIntent.putExtra(Intent.EXTRA_INTENT, mainIntent);
    this.startActivityForResult(pickIntent, MoreIconsConstants.REQUEST_PICK_APPLICATION)

Average time needed-->8-10 second

Second attempt I tried getting the list of apps in a list programmatically and showing the list my self in a dialog.-----> about 4 seconds...Faster but still slow.

Third attempt: I store the list in my preferences file so that in the future I load that list instantly...meanwhile getting the current list in the background and if there are differences update the list being shown to the user----Also about 4 seconds.

This is where it gets weird. Using Log statements i measured th exact time each method needs. If I load the list from the prefferences first and then load it by querying the package manager I takes again 4 seconds for the preferences method and 0.5 second for the querying method

If i load the list querying the package manager first and then load it from preferences it takes about 4 seconds for the querying method and 0.5 second for the preference method

So no matter what I do the first method takes a lot of time and the second is executed right away.

Is there an explanation for this or some other way to load this list faster?

I quote my code for both methods

loading list quering the package manager

private class AppAsyncCaller extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() { super.onPreExecute();  }
    @Override
    protected Void doInBackground(Void... params) {
        ArrayList<AppItem> allAppsInDevice2 = new ArrayList<AppItem>();
        long timeStart=System.currentTimeMillis();
        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null).addCategory(Intent.CATEGORY_LAUNCHER);
        List<ResolveInfo> packages=pm.queryIntentActivities(mainIntent, 0);
        for(int i=0;i<packages.size();i++){
            try{  
                String packageName=packages.get(i).activityInfo.packageName;
                AppItem item=getAppItem(packageName,false);
                if(item!=null){allAppsInDevice2.add(item);}
            }catch(Exception e){}
        }
        Log.w(Long.toString(System.currentTimeMillis()-timeStart),"duration using async caller");
        return null;
    }
    @Override
    protected void onPostExecute(Void result) {  super.onPostExecute(result);  }

 }

loading list from preferences method:

private class AppPrefsAsyncCaller extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() { super.onPreExecute();  }
    @Override
    protected Void doInBackground(Void... params) {
        long timeStart=System.currentTimeMillis();
        String allAppsListString = prefs.getString("allAppsListString", "");
        String[] tab=allAppsListString.split("_APPAPPAPP_");
        allAppsInDevice.clear();
        boolean updateAllApps=false;
        for(String s:tab){
            if(!s.equals("") && !s.equals(" ")){
                AppItem item=getAppItem(s,false); 
                if(item!=null){ allAppsInDevice.add(item); }
            }
        }

        Log.w(Long.toString(System.currentTimeMillis()-timeStart),"duration apo pref");


        return null;
    }
    @Override
    protected void onPostExecute(Void result) {  super.onPostExecute(result);  }

 }




public AppItem getAppItem(String packageName,boolean getIcon){
        AppItem item=new AppItem();
        item.packageName=packageName;
        ApplicationInfo ai=null;
        try {  ai = pm.getApplicationInfo( packageName, 0); } 
        catch (final NameNotFoundException e) {return null; }
        final String applicationName = (String) (ai != null ? pm.getApplicationLabel(ai) : "(unknown)");
        item.appName=applicationName;
        Intent intent = pm.getLaunchIntentForPackage(packageName);
        if(getIcon){
        Drawable icon=null;
            if (intent != null) {  try { icon = pm.getActivityIcon(intent); } catch (NameNotFoundException e) {} } 
            item.icon=icon;
        }

        return item;
    }
public class AppItem{
    String packageName;
    String appName;
    Drawable icon;
}