ExpandabeListView with checkbox in ViewPager Lag/slowness

I have a lag problem in expandablelistview which includes a checkbox in a viewpager. I even use viewholder pattern(i dont use for groups because they can be at most 4 so not needed. I use it on childs) but still something is causing lag when scroll or whatever i do in that page is a little bit laggy(no other pages causes lag, I have only 4 page in my viewpager.). Here is my code;

@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

    if (convertView == null) {
        infalInflater = (LayoutInflater) this.context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.task_group,parent,false);
    }

    LinearLayout bg = (LinearLayout) convertView.findViewById(R.id.taskGroupBg);
    TextView tv = (TextView) convertView.findViewById(R.id.closenessTv);

    CharSequence[] texts = context.getResources().getStringArray(R.array.closeness_texts);

    long id = this.getGroupId(groupPosition);

    if(id == -1){
        bg.setBackground(setGroupBackgroundColor(Color.parseColor(groupBgColors[0])));
        tv.setText(texts[0]);
    }else if(id == 0){
        bg.setBackground(setGroupBackgroundColor(Color.parseColor(groupBgColors[1])));
        tv.setText(texts[1]);
    }else if(id == 1){
        bg.setBackground(setGroupBackgroundColor(Color.parseColor(groupBgColors[2])));
        tv.setText(texts[2]);
    }else {
        bg.setBackground(setGroupBackgroundColor(Color.parseColor(groupBgColors[3])));
        tv.setText(texts[3]);
    }


    return convertView;
}

@Override
public View getChildView(final int groupPosition, final int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

    ViewHolder holder;

    if (convertView == null) {
        holder = new ViewHolder();
        convertView = infalInflater.inflate(R.layout.task_row,parent,false);

        // Create a ViewHolder and store references to the two children views

        holder.bg = (LinearLayout) convertView.findViewById(R.id.taskRowBg);
        holder.text = (TextView) convertView.findViewById(R.id.taskTv);
        holder.calendar =(LinearLayout) convertView.findViewById(R.id.calendar);
        holder.cb = (CheckBox) convertView.findViewById(R.id.taskCb);
        holder.dayRemain = (TextView) convertView.findViewById(R.id.dayRemainTv);
        //holder.cb.setEnabled(false);

        // The tag can be any Object, this just happens to be the ViewHolder
        convertView.setTag(holder);
    } else {
        holder = (ViewHolder) convertView.getTag();
    }

    final Task t = this.childData.get((int) getGroupId(groupPosition)).get(childPosition);

    lis = new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            checked.get((int)getGroupId(groupPosition))[childPosition] = isChecked;
            db = new TaskDb(context);
            if(isChecked)
                t.setStatus(DefaultValues.TASK_STATUS_COMPLETED);
            else
                t.setStatus(DefaultValues.TASK_STATUS_NOTDONE);
            db.updateTask(t);
        }
    };


    String text = t.getText();
    long id = this.getGroupId(groupPosition);
    if(id == -1)
        holder.bg.setBackgroundColor(Color.parseColor(rowBgColors[0]));
    else if (id == 0)
        holder.bg.setBackgroundColor(Color.parseColor(rowBgColors[1]));
    else if (id == 1)
        holder.bg.setBackgroundColor(Color.parseColor(rowBgColors[2]));
    else
        holder.bg.setBackgroundColor(Color.parseColor(rowBgColors[3]));

    holder.text.setText(text);
    // holder.dayRemain.setText(findHourDif(System.currentTimeMillis(),t.getRemindDate()));
    int status = t.getStatus();

    long curTime = System.currentTimeMillis();
    if(t.getRemindDate() < curTime && status == DefaultValues.TASK_STATUS_NOTDONE)
        t.setStatus(DefaultValues.TASK_STATUS_OVER_NOTDONE);
    else if(t.getRemindDate() < curTime && status == DefaultValues.TASK_STATUS_COMPLETED)
        t.setStatus(DefaultValues.TASK_STATUS_OVER_DONE);

    status = t.getStatus();
   //holder.cb.setTag(childPosition);
    holder.cb.setOnCheckedChangeListener(null);
    holder.cb.setChecked(checked.get((int)getGroupId(groupPosition))[childPosition]);
    holder.cb.setOnCheckedChangeListener(lis);
    if(status == DefaultValues.TASK_STATUS_OVER_DONE || status == DefaultValues.TASK_STATUS_OVER_NOTDONE) {
        holder.text.setPaintFlags(holder.text.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
    }
    else {
        holder.text.setPaintFlags(holder.text.getPaintFlags() & ~Paint.STRIKE_THRU_TEXT_FLAG);
       // holder.text.invalidate();
    }

    DateConverter dc = new DateConverter(context,t.getRemindDate());
    String[] dateStr = dc.getTaskDateFormat();
    holder.calendar.removeAllViews();
    holder.calendar.addView(new DrawCalendar(context, dateStr));//drawCalendar(dateStr[0],dateStr[1]));
    holder.calendar.invalidate();


    return convertView;

//My Calendar drawer probably has no effect but still i will put

 public class DrawCalendar extends View {

private RectF small = new RectF(),big = new RectF();
private Paint p = new Paint();
private Paint textP = new Paint();
private Paint.FontMetrics fm = new Paint.FontMetrics();
private String[] dates;
private float radiusSize = 20f;

public DrawCalendar(Context context,String[] dates) {
    super(context);
    this.dates = dates;
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    int width = canvas.getWidth();
    int height = canvas.getHeight();

    int smallH =height/2;

    small.set(0, 0, width, smallH);
    p.setColor(Color.parseColor("#6C4D4D"));
    p.setStyle(Paint.Style.FILL);
    p.setAntiAlias(true);
    drawAsymmetricRoundRect(canvas, small, new float[]{radiusSize, radiusSize, 0, 0}, p);
    /*p.setStrokeWidth(2);
    p.setStyle(Paint.Style.STROKE);
    p.setColor(Color.parseColor("#444444"));
    drawAsymmetricRoundRect(canvas, small, new float[]{10, 10, 0, 0}, p);*/


    textP.setTextSize(60);
    textP.setColor(Color.parseColor("#dddddd"));
    textP.setTextAlign(Paint.Align.CENTER);
    textP.getFontMetrics(fm);
    int textPos = smallH / 2 + smallH / 4;
    canvas.drawText(dates[1], width / 2, textPos, textP);

    big.set(0, smallH, width, height);
    p.setStyle(Paint.Style.FILL);
    p.setColor(Color.parseColor("#fafafa"));
    drawAsymmetricRoundRect(canvas,big,new float[]{0,0,radiusSize,radiusSize},p);
    /*p.setStyle(Paint.Style.STROKE);
    p.setColor(Color.parseColor("#444444"));
    p.setStrokeWidth(1);
    drawAsymmetricRoundRect(canvas,big,new float[]{0,0,10,10},p);*/

    textP.setTextSize(45);
    textP.setColor(Color.parseColor("#444444"));
    textP.setTextAlign(Paint.Align.CENTER);
    textP.getFontMetrics(fm);
    canvas.drawText(dates[0], width / 2, smallH + textPos, textP);

}
private void drawAsymmetricRoundRect(Canvas canvas, RectF rectF, float[] radii, Paint paint) {
    float topLeftX = rectF.left + radii[0];
    float topLeftY = rectF.top + radii[0];
    float topRightX = rectF.right - radii[1];
    float topRightY = rectF.top + radii[1];
    float bottomRightX = rectF.right - radii[2];
    float bottomRightY = rectF.bottom - radii[2];
    float bottomLeftY = rectF.bottom - radii[3];
    float bottomLeftX = rectF.left + radii[3];

    /*float[] radii is a float array (length = 4), that stores sizes of radii of your corners
     (clockwise, starting from top-left corner => {topLeft, topRight, bottomRight, bottomLeft}).*/
    RectF topLeftCorner = new RectF(rectF.left, rectF.top, topLeftX + radii[0], topLeftY + radii[0]);
    RectF topRightCorner = new RectF(topRightX - radii[1], rectF.top, rectF.right, topRightY + radii[1]);
    RectF bottomRightCorner = new RectF(bottomRightX - radii[2], bottomRightY - radii[2], rectF.right, rectF.bottom);
    RectF bottomLeftCorner = new RectF(rectF.left, bottomLeftY - radii[3], bottomLeftX + radii[3], rectF.bottom);

    canvas.drawArc(topLeftCorner, 180, 90, true, paint);
    canvas.drawArc(topRightCorner, 270, 90, true, paint);
    canvas.drawArc(bottomRightCorner, 0, 90, true, paint);
    canvas.drawArc(bottomLeftCorner, 90, 90, true, paint);
    canvas.drawRect(topLeftX, rectF.top, topRightX, bottomLeftY < bottomRightY ? bottomLeftY : bottomRightY, paint); //top rect
    canvas.drawRect(topLeftX > bottomLeftX ? topLeftX : bottomLeftX, topRightY, rectF.right, bottomRightY, paint); //right rect
    canvas.drawRect(bottomLeftX, topLeftY > topRightY ? topLeftY : topRightY, bottomRightX, rectF.bottom, paint); //bottom rect
    canvas.drawRect(rectF.left, topLeftY, bottomRightX < topRightX ? bottomRightX : topRightX, bottomLeftY, paint); //left rect
}