SlickGrid
A lightning fast JavaScript grid/spreadsheet
... virtual rendering where only what’s visible on the screen plus a small buffer is rendered. As the user scrolls, DOM nodes are continuously being created and removed. These operations are highly tuned to provide optimal performance under all browsers. The grid also adapts to the direction and speed of scroll to minimize the number of rows that need to be swapped out and to dynamically switch between synchronous and asynchronous rendering.