How to get records from DataView based on selected listitem

Hi All

I want to retrieve 25000 records from dataview based on the selected listitems in the listbox.

But the problem is in the code forloop is there which contains 23 if conditions. each if condition checks and get the data from Dataview.

Here performance is slow. WebPage is keep on Loading. I am not able to see the data in UI.

Can anyone please share your ideas. It would be very helpful