Use a Block Page? Does it slow down Browsing?
I am trying to understand if using a Block Page always slows down page Load or if it is only slow on blocked sites?
The Settings Page says the following:
Display a block page when a domain is being blocked. This may slightly increase page load time and an HTTPS warning may appear in some cases. When disabled, blocked queries will be answered with the unspecified address (0.0.0.0 or ::).
The logic here is that if you do not use a block page the block is happening on the DNS level by giving an answer with the 0.0.0.0/:: address. It depends on the device how the response is handled but in many cases it will say that the server is unreachable (very fast). If you configure to reply with a block page NextDNS will return an IP address on which the bock page is hosted. Now the device will connect to this web server to retrieve the (block) page. If it is a page served over HTTPS and the root certificate is not installed in the root certificate store on the device it will give a certificate warning as it will not trust the certificate presented which is signed by the root CA of nextdns.
So in short, the DNS unspecified address is quicker to answer without any additional action but the response page might be nicer to the user but adds extra steps which can cause some latency.
For domains that are not blocked it does not matter as Greg stated as it will return the normal answer through DNS.