I thought I filed a bug on this years ago, but I can't find it. One of the things that makes WipeContainingBlock expensive is when it recursively decides that it's in yet another situation that requires destroying the containing block. I think this could be avoided if we had a way to reconstruct all the children of a frame without reconstructing the frame itself. This would allow WipeContainingBlock to step up to "all of my siblings" but it wouldn't need to destroy the parent, and thus wouldn't risk triggering itself recursively... at least in most cases. It's worth thinking about whether it's worth adding such a mechanism.