Greetings from Syncfusion Support.
We have analyzed the reported scenario. We are also able to reproduce the reported problem delay in vertical scrolling at our end.
We have resolved this problem by using virtualization while scrolling GanttControl Vertically. i.e. while vertical scrolling, we have updated the UI by removing and adding the Gantt Node’s based on ScrollViewer’s vertical scroll offset. In your case, you have loaded large number of inline items. So, it will take some time to generate and rendered in UI.
To avoid the delay, you can enable the differed scrolling (it means that the view does not scroll until mouse click is released) in Gantt Grid’s Scroll Viewer in GanttControl’s loaded event as like below code snippet.
public partial class MainWindow : ChromelessWindow
this.Gantt.Loaded += Gantt_Loaded;
private void Gantt_Loaded(object sender, System.Windows.RoutedEventArgs e)
Border border = (Border)VisualTreeHelper.GetChild(this.Gantt.GanttGrid, 0);
ScrollViewer viewer = (ScrollViewer)VisualTreeHelper.GetChild(border, 0);
viewer.IsDeferredScrollingEnabled = true;
Please find the sample from the below link,
Muneesh Kumar G.