That has a small number of long columns down the entire page, which doesn't give any of the benefits of having columns. Actually, it's only worse in terms of readability, as a big factor is how well your brain can spatialize the location of what you're reading for backwards jumps or subconscious memory palace stuff. Here that's complicated by the mental overhead of "I'm halfway down the page, but the page is really twice as long as it is, so that's actually 1/4 of the way through."
Proper column layout involves limiting columns to screen height, probably by paginating. Then the reader can perceive the text as a tree of Page > Column > Paragraph > Row. Tangentially, I think there are studies positing that this, helped by the notion of physical pages in space, is what's behind the readability advantage of books.
Alternative to pagination is scroll-direction: horizontal. Now the experience is even closer to reading a book. And to Windows 8! IMO there's a shortage of novelty sites with true (non-slideshow or carousel) horizontal scrolling.
The NASM website is an example of this. Personally, I don't like it and would prefer a single column.