HoveredRowAdorner and SelectedRowAdorner become very sluggish when the GridItemsControl has more than 70 rows.

[Sally-Xu]

I tried to add 10 rows, 30 rows, 50 rows, 70 rows, and 100 rows of data to the GridItemsControl. When the row number <50, the Grid is quite responsive. But when the row number > 70, the Grid becomes very sluggish, the HoveredRow and SelectedRow are totally out of sync with the mouse position.

[BSick7]

If you come across performance issues, run the Chrome devtools profiler and send the dump.