Just found that the DNS prefetch requests created from here are not helpful. The reason is that the suffix of this origin attributes is empty (I guess that's because the element's doc is about:home).
For example, when opening a new tab, a prefetch request is created to fetch www.wikipedia.org. This creates a new record with a hash key [www.wikipedia.org]<> in DNS cache. Then, when a user navigates to www.wikipedia.org, another DNS query will be created with the hash key [www.wikipedia.org]<^partitionKey=%28https%2Cwikipedia.org%29>. Since the suffix of two hash keys are different, the previous prefetch request has no effect at all.