And there is funny fact. I've put DateTime start and DateTime end.
DateTime start is set before InitializeComponent();
DateTime end is set in Window.Loaded.
Both of them is set to DateTime.Now. And TimeSpan shows me .TotalSeconds = end-start - so it represents total time to load window.
Now something funny:
Total time when LOADING DATA (3000+ items into ListBox, with template as in first post):
Time is (sec) :3,0521746
Total time when NOT LOADING DATA - just to build page, with comments in 3 line :
pL = FastSellSearchClass.lista.Where(x =>
x.nazwa.ToLower().Contains(query.ToLower()) || x.kod.Contains(query)
&& x.wID ==
//testlv.ItemsSource = pL;
Time is (sec): 3,0821763
Values are almost the same.
So i have to understand it as : loading any telerik control took 3 second in quiet fast PC. Loading data tooks less than 1 sec.
Is that any bug in telerik controls or what, becouse I really dont understand it.