Actually, 450 ms was already a cache hit. The response time would be 530 ms on the first query of google.com:

  ./godnsbench -c 1 -q google.com -a https://sky.rethinkdns.com/dns-query
  ...
  2025/05/05 02:50:14 [info] Average per query: 532.1144ms

Subsequent queries for google.com within a few minutes would result in a slightly shorter response time, like my second comment above.

  ./godnsbench -c 1 -q google.com -a https://sky.rethinkdns.com/dns-query
  ...
  2025/05/05 02:50:48 [info] Average per query: 468.5749ms

  ./godnsbench -c 1 -q google.com -a https://sky.rethinkdns.com/dns-query
  ...
  2025/05/05 02:55:04 [info] Average per query: 472.1229ms

Some of the lengthy response times originate from the overhead of DNS over HTTPS. If we switch to the DNS over TLS version of Rethink DNS, there will be about a 240-320 ms improvement in response time.

  ./godnsbench -c 1 -q google.com -a tls://max.rethinkdns.com
  ...
  2025/05/05 02:50:26 [info] Average per query: 290.4762ms

  ./godnsbench -c 1 -q google.com -a tls://max.rethinkdns.com
  ...
  2025/05/05 02:50:51 [info] Average per query: 145.1868ms

However, 290ms is still quite a large delay for DNS queries, which makes webpage rendering a quarter of a second slower the first time you visit it.