We have a grid that utilises a GroupSummaryView, and allows for selection of multiple rows. Selection of the rows is very slow and gets slower the more rows that are selected. With a grid containing 74 rows (grouped across 3 groups), selecting all the rows by scrolling to the last row and use shift-click causes IE 8 to display the 'Stop running this script ?' web browser is running slowly message.

If I deselect the 'Show In Groups' checkbox (via the drop down from the column headings) and try the same multi-select, performance is much quicker and no IE8 warning message is shown.

We have no code that is executed on row select. The performance is currently unacceptable to our users.

The grid is set up as below:

GroupSummaryView<BookingRowItem> groupSummaryView = new GroupSummaryView<BookingRowItem>();
bookingsGrid = new Grid<BookingRowItem>(bookingListStore, columnModel);