:| What?
Misinformation, again.
uBO prevents DNS requests from being made in the first place for requests which are meant to be blocked. This way the browser will know faster that a network request is meant to be blocked, it does not have to wait for a DNS resolver to respond.
Additionally, as a result of being in-browser, uBO is also able to collapse the placeholder counterpart of any of network requests which were cancelled.
> does not have to wait for a DNS resolver to respond
The browser (or the system) caches DNS responses and the query for a blocked domain won't be repeated for quite some time.