EnableExplicit

Define EventID
Define a
Define StartTime
Define ElapsedTime

If OpenWindow(0,0,0,500,400,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  ListIconGadget(1,10,10,480,380,"",400,0)
  SendMessage_(GadgetID(1),#WM_SETREDRAW,0,0)
 
  StartTime = ElapsedMilliseconds()
 
  For a=1 To 10000
    AddGadgetItem(1,-1,"Item "+Str(a),0,0)
  Next
 
  SendMessage_(GadgetID(1),#WM_SETREDRAW,1,0)
 
  ElapsedTime = ElapsedMilliseconds()-StartTime
  
  MessageRequester("",Str(ElapsedTime)+" ms. für 10.000 Einträge. Normalerweise dauert das circa 15-20 Mal länger.",0)
  
  Repeat
    EventID=WaitWindowEvent()
    If EventID = #PB_Event_CloseWindow
      End
    EndIf
  ForEver
EndIf