how to add elements to Listview.builder without rebuilding all the previous items

Question

i use Listview.builder with a List of items in flutter , when the user scroll down i listen the the scroll controller than i get more data from firebase Firestore

the problem that when more data added to the itemlist all the previous items of the Listview.builder rebuilded automaticaly

ex : the list.lenght is 50 ,when i scroll down i get 20 more items and add them to the item list , the 50 previous item are reubilded automaticaly (like the image ) enter image description here

this make the app bugging some times

any help ?

this is my Listview.builder code

    Selector<postsPage_modelView,Tuple2<List<Post>,bool>>(
      selector: (_,provider)=>Tuple2(provider.postsList, provider.isLoading),
      builder: (_,data,__)=>ListView.builder(
        shrinkWrap: true,
        physics: const NeverScrollableScrollPhysics(),
        itemCount: data.item1.length+1,
        itemBuilder: (context,index){
          if(index == data.item1.length){
            if(data.item2) {
              return const Center(
                child: CircularProgressIndicator()
              );
            }
            return const Center();
          }
          Post tmp = data.item1[index];
          return PostItem(post: tmp);
        },
      ),
    ),

thank you all