I noticed my uploads to Flickr got slower since I changed my DNS entry to 18.104.22.168 on my home network.
After some investigation here it looks like with the 22.214.171.124 resolver from my home connection here in Hong Kong will point to up.flickr.com to 126.96.36.199 (which looks to be in the US, about 170ms and 11 hops away from a traceroute).
My previous DNS resolver points up.flickr.com to 188.8.131.52, which is much closer (apparently Korea; 9 hops, but 2.5-3ms latency only).
Besides latency, this also explains the big throughput difference I’ve been observing (5 MB/s peak with 184.108.40.206 resolver, vs. 30-40 MB/s peak with my previous DNS).
Is there something Cloudflare can do to optimize the resolution?