When you enable staging, Liferay must sweep through and duplicate all content (one for the staging side and one for the prod side). The more content you have, the longer this will take. And, of course, errors could arise that may be prohibitive if the logic for the staging has difficulty handling the split.
I don't know if this is a valid example, but consider if you have two web content articles pointed at the same image; when the logic is duplicating the first content it should duplicate the image (so you get the staging support). But when it comes time to duplicate the second content, what happens then? It's very own duplicate of the image, or will the system be able to find the staging image that was previously created?
Like I said, this may not be a good example of a possible failure because I haven't actually tried it. But it should point out, however, how this duplication process can lead to all kinds of odd outcomes.
