Bug report

Expanding all detail templates via expandRow() on a Grid with many records and no paging enabled takes really long time

Reproduction of the problem

 - Open

Dojo: https://dojo.telerik.com/aBAseraz

- Click Expand All button (the page gets non-responsive for 70 seconds)

Expected/desired behavior
The above Grid shall expand all detail templates for a reasonable less amount of time. For example: 

• https://dojo.telerik.com/aBAseraz/5