dialog box twice and takes time to open on click using speed dial in flutter

Question

i am using speed dial in floating action button for dialog box it takes time to open when i have connected with the api data and user click twice on the button then its open twice [this is the code of the speed dial where i am opening the dialog box here i am attaching the image]

(https://i.stack.imgur.com/PeyAU.png)
[this is the package i am using in floating action button here i am attaching the image]
(https://i.stack.imgur.com/8mNlY.png)

i want it open fast on click and it opens once and allow to click once here is the code :

floatingActionButton: Column(
    crossAxisAlignment: CrossAxisAlignment.end,
    mainAxisAlignment: MainAxisAlignment.end,
    children: [
      Padding(padding: const EdgeInsets.all(10.0),
          child: SpeedDial(
            foregroundColor: Colors.blue,
            backgroundColor: Colors.white,
            animationAngle: 45,
            direction: SpeedDialDirection.up,
            spaceBetweenChildren: 10,
            animatedIcon: AnimatedIcons.menu_close,
            children: [
              SpeedDialChild(
                  child: const Icon(Icons.content_paste_search),
                  label: 'Search',
                  onTap: () async {
                    print("yes");
                    var dataValue = await showDialog(
                        context: context, builder: (BuildContext) {
                      return regularizationfilter(
                          _fetchRegularizationList, filterdData,
                          dropdown_employee_list, filterdatavalue
                      );
                    }
                    );
                    filterdatavalue = dataValue;
                    setState(() {

                    });
                  }
              ),