Performance Issue When starting Android Music Player Activity During database population

I am writing an application where the database gets created and as soon as 1 insertion in database takes place, the startActivity() API is getting called in a different thread. The startActivity() gets called instantly, but it takes a lot of time for the the onCreate of that activity get called. Following is the code where I am starting the activity :

void startPopulatingDb(String[] list) {

    if(list == null)
        return;

    openDB();
    MetaDataRetriever mdr = new MetaDataRetriever();

    for(int i = 0; i < list.length; i++) {
        ContentValues values = new ContentValues();
        String media;

        media = devicePath+"/"+list[i];
        //Log.d("SOURAV", media);
        MetaData entry  = mdr.getMetaData(media);

        if(entry != null) {
            values.put(MusicEntry.COLUMN_NAME_TITLE, entry.getTitle());
            values.put(MusicEntry.COLUMN_NAME_ARTIST, entry.getArtist());
            values.put(MusicEntry.COLUMN_NAME_ALBUM, entry.getAlbum());
            values.put(MusicEntry.COLUMN_NAME_GENRE, entry.getGenre());
            values.put(MusicEntry.COLUMN_NAME_URI, entry.getUri().toString());

            database.insert(MusicEntry.TABLE_NAME, "unknown", values);
            getApplicationContext().getContentResolver().notifyChange(
                                                MusicPlayerSQLiteHelper.DB_URI, null);

            if(mediaCount == 1) {
                Thread thread = new Thread() {
                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        Intent startIntent = new Intent(getApplicationContext(), MainActivity.class);
                        startIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                        Log.w("MusicPalyer", "LaunchOrKillService::Starting Activity");

                        startActivity(startIntent);
                    }
                };
                thread.start();
            }
            Intent dataSetChangeIntent = new Intent();
            dataSetChangeIntent.setAction(MODIFY_DATA_SET);
            sendBroadcast(dataSetChangeIntent);

            mediaCount++;
        } else {
            mediaCount = 0;
        }       
    }
}

Any ideas why there is so lag in launching activity ? Thanks in advance.