What is modern wood vs. old growth wood all about?

when it comes to selecting wood for windows

What is modern wood vs. old growth wood all about?  .. Modern wood derived from tree farms grows fast due to management practices and the application of fertilizers. This is not necessarily bad because we need a steady supply of lumber for all sorts of uses. However, when it comes to selecting wood for windows, speedy growth is not always better. Fast-growing wood not only has growth rings that are further apart, but also a higher percentage of earlywood or sapwood. This earlywood is rich in sugars. Wood with more widely spaced growth rings is less dense and therefore not as durable. The sugars feed the tree as it grows, but are also attractive to insects who don't care if the wood is a live tree branch or your window sill.