Because the display is the bottleneck.

Can you present some real life scenario where this is an issue? Let's say you want to display the result on a webpage - the bottleneck of creating a DOM structure with all <div>s and similar tags would be much more significant, but what you should do instead is just create a scrollbar, and enough divs to fill the scrolling area, and as a user drags the scrollbar's slider, you adjust the height of the divs by the modulo of scrolled_height / div_height, and then populate those divs with the right values for the scrolled range (that you can easily compute on each scrollbar event).

The only reason to care about those microseconds is when you want to really fill the console with millions of lines, but you shouldn't actually want to do that, I think ever?