how to decrease time of long running method in c#(windows form)

Question

I am trying to decrease a form load time 

 

Main.cs

private void UTMaster_ToolClick(object sender, ToolClickEventArgs e)  //when I click on tag then this will call
{
  OrganisationMethod(sender,e);
}

private void OrganisationMethod(object sender, ToolClickEventArgs e)
{
   Form frms = (Form)Activator.CreateInstance(Type.GetType(strtagname));
   Type ObjType = frms.GetType();
   MethodInfo method = ObjType.GetMethod("ShowOrganisationForm"); //ShowOrganisationForm is a form


   ParameterInfo[] Arrayparams = method.GetParameters();

   if (Arrayparams.Length == 0)
   {
      method.Invoke(frms, new object[0]);
   }
   else
   {
       //frms.Load += new (method);
       object[] paramsArray;

       paramsArray = new object[] { e.Tool.propertytag.Tag.ToString() };

       method.Invoke(frms, paramsArray);

   }
}

organiseform.cs

public void ShowOrganisationForm()
{
      DataSetControl();     //this method take too much time to load
   this.Show();
}

private void DataSetControl()
{
   //multiple combox fill code here
}

I am working with windows form 

 

I am trying to decrease the form load time but not work please help