Grid's Virtualization and Grouping Support

[Aaron]

We are evaluating the Telerik KendoUI Web Framework and want to identify it's potential. Therefore we put some effort in developing a small web application containing a Grid widget. The Grid's DataSource is based on a remote JSON source which contains about 5000 data objects.
We wanted to make heavy use of the filter, sorting, grouping and/or paging functionality because these are features which are often required by our customers.

Basically we are satisfied with the KendoUI Web Framework. Although we miss some great features we know from other Telerik products (like the Silverlight RadControls) we are happy with it's spectrum of functionality. But the greatest downside (from our point of view) is the Grid's lack of support for virtualization used together with grouping. We were not able to find a good solution to make the Grid highly responsive and user friendly while supporting large sets of data.
In our case the filtering works like charm when the virtualization is enabled. But when it comes to grouping there is this strange effect for collapsed groups: the groups are not arranged one below the other. The user has to scroll/page through large empty areas before the next group appears. This is very unpleasant to use.
When the virtualization is disabled, the filtering is much slower (but filters in an acceptable amount of time). Also the interaction on rows has a very high delay (like selection or activating and collapsing groups).

Do you have any tips regarding the grouping?
Are there plans to work on those issues in future releases of KendoUI?

EDIT: I'm referring to and voted for this feedback.

[Dimo]

Hi Aaron,

Thank you for your interest in Kendo UI.

Virtual scrolling is very similar to paging, because data is retrieved from the datasource and displayed in portions, which are practically pages. This is the reason for not showing the next group when you collapse the last visible one.

Filtering may be slower with virtualization turned off, if you are using client data operations with a huge number of rows. In this case, please use server data operations.

http://docs.kendoui.com/api/framework/datasource#configuration-serverFiltering

http://demos.kendoui.com/web/grid/remote-data.html

Selection or group expand-collapse performance can also be slower with a huge number of rows due to slow execution of :not CSS selectors. Please consider using virtual scrolling or paging with a reasonable page size.

Regards,
Dimo
Telerik

[Aaron]

Thanks for the explanation.
It would be great if the Grid's support for virtualization and grouping is extended in future releases. We would wish a behavior like this with grouping enabled in the RadGridView.