welp. for every single domain you interact with, you gotta do a dns lookup. visit a modern website like yahoo, cnn, wapo, whatever and that will be like 100 dns requests. your device hits your router, if it has no answer, it recursively goes up the line getting an answer. do that 100 times. that is just for resolution. you still gotta actually hit that endpoint and get whatever it is you are trying to get.
so if your dns is slow, there is a tremendous amount of latency added to virtually everything that you do. just because you can hit nextdns in 12ms does not mean the e2e duration for a single dns-then-fetch is going to be in the realm of 12ms. if nextdns doesn't have the answer it needs to go find it.
I use my local router as a DNS cache/proxy for this exact reason, though i doubt 12ms (or 24ms) will mean much in the grand scheme of things compared to downloading a 25MB webpage which is mostly tracking code and ads.
Yes, if we were in the "good old days" of slim websites, 12ms may be noticable, but today, with webpages taking up lots and lots of storage that is served with every connetion, i seriously doubt you'll notice.
Besides that, every browser and modern operating system will cache DNS records for whatever the TTL from the upstream DNS is set to.
so if your dns is slow, there is a tremendous amount of latency added to virtually everything that you do. just because you can hit nextdns in 12ms does not mean the e2e duration for a single dns-then-fetch is going to be in the realm of 12ms. if nextdns doesn't have the answer it needs to go find it.