Latency isn't the important measurement — it's the actual time to resolve. This will be significantly longer than the ping latency.
Unbound, recommended for use with Pi-hole, can be configured to log this by enabling "log-replies" in unbound.conf⁽¹⁾ where the time to resolve will be logged in seconds.
my biggest gripe with NextDNS is not having an ability to add custom blocklists. I'd gladly pay for it even if there was a paid tier with this feature.
I'm aware of adding domains one by one, but I want to add some lists like Hagezi Threat Intelligence Feed which is not available in the blocklists, and these blocklists have >500k domain list.
I'm currently using Blocky as my DNS resolver. It works fine and is super fast because of the fine control over caching, but I'm disappointed with its memory footprint. 400MB for a total blocklist of 1.3M domains
I'm currently seeing 12ms latency to my upstream NextDNS server. On my home network I "proxy" it with a forwarding/caching DNS server on my router, so for "the usual suspects", latency is not an issue.
On the go, over 5G, those 12ms won't make much of a difference.
Considering that people deploy PiHole on Raspberry Pi W models, over wifi, you won't lose much running NextDNS, but you gain dns blacklisting on all networks, as opposed to just your home network (or via VPN)
I'm not sure how that could be. Even if it's your first ever request to the host, the latency is a one time thing and then it's cached. Even an extra 100ms for DNS latency is going to be unnoticeable compared to an empty browser cache and having to download a bunch of images
As for the latency - is it really noticeable?