I have a test app, which has two grids. One just a hierarchical display of all the employees in the table, with two sorted columns,'Company' and 'Department'. [As the data table is configured to have multiple companies and departments, i get a hierarchical display of employees]. The second grid displays more Employee Information and displays only employees who are dragged onto it from the hierarchical grid.  

Basically when the user drags a Row [either a data row or a groupby row], i fetch the non-groupby rows under it and build up a comma separated list of employees which could be used to fetch the data for the detail grid. Now this is alright for 100 employees selected at once. But I am currently testing a grid with 50K employees. I have a scenario where a company has over 30K employees and if the user drags one of this company, it takes eternity to build up the csv file.

Is there any other alternative ?? Fetching the data doesnot take long at all, but building the csv does !