It would be useful to know which blocklist is responsible per blocked query. For instance, if I find myself going through a lot of trouble whitelisting things, I can imagine that if they were all blocked due to a single list, I may want to consider disabling that list entirely. But I don't know that I have a way to easily identify that right now by looking at blocked queries. If they just displayed the list(s) they exist on inline, that could be very useful in identifying impact of various list inclusion.
I don't think it has to happen in realtime before the DNS response is delivered, per the performance concern. In fact, it only really would need to happen when the blocked queries were viewed. If performance were still an issue even with that, then it could be an option as to whether to display it or not.
I also realize that multiple blocklists could carry the same domain- in such an instance, the expectation would be that all lists blocking a given domain would be listed beside it.
Thanks for the suggestions, but my aim here with this feature was to make this information readily accessible, so it becomes apparent without a lot of manual effort each time for the type of reasoning I described.