为什么我的gridview如此不顺畅？

Question

我在MainActivity中使用AsyncTask从DB读取所有数据，并使用静态SparseArray来保存这些数据，在getView中我立即使用SparseArray。但它仍然不顺利。 AsyncTask

@Override 
protected Void doInBackground(Integer... position) {

    for (int i = 0; i < position[0]; i++) {
        int dayOfWeek = i % 8 - 1;
        int onClass = i / 8 + 1;
        Item item = new Item();

        if (i % 8 != 0 && TimeUtil.judgeTime(context, dayOfWeek, onClass)) {
            item.setColor(1);
        }

        if (i % 8 != 0 && TimeUtil.hasSchool(context, dayOfWeek, onClass)) {
            Curriculum curriculum = Curriculum.getCurriculum(context, dayOfWeek, onClass);
            courseId = curriculum.getCourseId();
            buildId = curriculum.getBuildingId();
            roomNum = curriculum.getRoomNum();

            String nickName = getCourseInfo(context, courseId);
            String buildName = getBuildInfo(context, buildId);

            item.setNickName(nickName);
            item.setPlace(buildName);
            item.setRoomNum(roomNum);

            item.setHasCourse(1);
        }

        itemCache.append(i, item);
    }
    return null;
}

和getView

@Override
    public View getView(int position, View convertView, ViewGroup parent) {

        convertView = LayoutInflater.from(context).inflate(R.layout.gridview_item, null);

        courseText = (TextView) convertView.findViewById(R.id.grid_item_nick);
        placeText = (TextView) convertView.findViewById(R.id.grid_item_palce);
        roomText = (TextView) convertView.findViewById(R.id.grid_item_room);




        if (position % 8 == 0) {
            convertView.setBackgroundColor(getResources().getColor(R.color.gray));
            courseText.setText("第" + onClass + "节");
            return convertView;
        }


        ItemLoadAsyncTask.Item item = ItemLoadAsyncTask.itemCache.get(position);
        if (item != null && item.getColor() == 1) {
            convertView.setBackgroundColor(Color.WHITE);
        }
        if (item.getHasCourse() == 1) {
            setInfoView(item);
        }
        return convertView;

    }