[jdudek]

> We could insert new list items into the existing DOM, but finding the right place to insert them is error-prone, and each insert will cause the browser to repaint the page, which is slow.

I don’t think the last part is true. Browsers don’t repaint (nor they reflow) the page until it’s really needed. So if you have a loop that modifies the DOM multiple times, but does not read from the DOM, there performance hit described by the author should not occur.