You have no idea what is the purpose of a DNS, do you? Choosing Google DNS doesn't mean adding a man in the middle. Your computer needs the DNS data one way or another, there is ALWAYS a DNS server. Whether it's Google or not. Google DNS doesn't make sites go faster...... It isn't a CDN like CloudFlare. Sites appear to load faster because Google DNS is really well optimized. If you use a benchmarking tool, chances are it's faster than your ISP's DNS servers.