From the sounds of the article, that 300 milliseconds wasn't much addition or math or number crunching but essentially book keeping and querying. A lot of that

From the sounds of the article, that 300 milliseconds wasn't much addition or math or number crunching but essentially book keeping and querying. A lot of that crunching is either whittling through DOM traversals. I've heard that rule of thumb that there are 5-9 machine instructions before JMP or CALL which you can find if you search "instructions per branch cpu" If I had a database of 4,000 links and instantiated a function event handler to each one, that would be slow. But if I could invert the problem and test if the clicked object is inside an active query resultset, that could be fast. It could be automatic.