SlickGrid (http://wiki.github.com/mleibman/SlickGrid/examples) is very fast and it uses just divs for the grid. It has still limited features but perhaps grid should be implemented with just divs to allow for maximum flexibility?
So, for sure it can be done without "using many tables for a single table". It accounts for improvements in efficiency as all agree, especially if you add buffering, and as dhtmlxGrid shows, you can still do a lot with such approach.