Infinite Scroll
A grid doesn’t have to page. With PagingMode set to Virtualize it shows one long list and loads the next rows as the end of it comes into view, so a user scrolls through thousands of records as if they were all there. Search, sorting and totals work the same way.
Four Thousand Opportunities, One List
Scroll down: every opportunity in the sample data is in the list, 50 at a time. The footer counts how many of the matching rows have loaded, and the totals row counts and adds up all of them, not only those on screen. Search for an account to start again from the top.