I am looking for some stats on current browsers for how long it takes to render a table using plain HTML versus a hacked-up CSS puritan method that avoids using actual TABLE, TR, TD etc. tags.
I am not looking for what's proper, only for what's faster, particularly on Firefox 3, although I am also interested in the stats for other browsers. Of course TABLE tags are designed for tables. That's not the question.
In general, I would say use <table> for tabular data. However, if the table is very long (say, over 100 rows) and the number of columns is low (~3), using divs to emulate rows would result in a much smaller markup footprint. This is especially relevant if you are using DOM searching javascript (as provided by the many JS libraries), as it would benefit to reduce the DOM tree size.
This is from experience, I had such a table and was looking for optimizations - moving to a div based display cut the HTML generated to a third and was a big improvement in DOM traversal performance.