You will not have any extra latency once the DNS resolution is done. The resolution has to be done a way or another, by default this is your ISP and they usual

You will not have any extra latency once the DNS resolution is done. The resolution has to be done a way or another, by default this is your ISP and they usually suck. I had hand-picked DNSes before (there is a utility that tests plenty of them from your connection) and after adding a pihole on a simple RPi it was even faster.