This is an individual task to split the parent task into smaller chunks. It may be declined if the expected performance improvement is not worth the expected investment.
Note that this requires additional care as we'd be moving from a whole document to a document containing only the body, and this is the only pass where we do that.
If we're implementing this task, it is worth considering passing a DOM document directly from Parsoid to this pass, without serializing to text in the middle.