Flutter Multi-Threading Issue when uploading multiple url gifs/images

Question

I'm consistently receiving multi-threading issues when downloading a list of gifs from giphy.com. Each time my app crashes and logs a "I/Choreographer(15955): Skipped 104 frames! The application may be doing too much work on its main thread." type error. I haven't come across any threading solutions for flutter. Here is my code...

 Future<Null> giphy() async {
    var _searchterm = _searchController.text.toString().replaceAll(' ', '+');
    String url = GIPHY.com;

    //var httpClient = createHttpClient();
    var response = await http.get(url);
    Map data = json.decode(response.body);
    //print(data['data']);
    var gifs = new List();
    for (var items in data['data']) {
      var images = (items['images'] as Map);
      var downsized = (images['downsized'] as Map);
      var urls = downsized['url'].toString();
      gifs.add(urls);
    }

    setState(() => giphyUrls = gifs);
    _neverSatisfied();
  }

giphyUrls is a public list that feeds into a gridview builder.