question regarding ad blocking, white pages, and "slow loading"

Apologies if this has been asked/discussed already:

I have noticed that, when an ad-blocker is disabled (or browsing incognito) on the Verge, pages draw immediately when you go to a new page. However, as soon as an ad-blocker is enabled, new pages show a blank screen for about 5 seconds before displaying the content. The dead giveaway is that the scroll-bar is visible but the entire page is white. Then, miraculously, everything appears at once.

I assume this is to discourage ad-blocking, but just curious if you are willing to verify that that is indeed what is happening?