Thanks to @giridharkannan in: https://community.atlassian.com/t5/Bitbucket-questions/Slow-SSH-clone-pull-push/qaq-p/953843
SSH supports both IPv4 and IPv6 and prefers IPv6 if the DNS retrieves AAAA record, but my ISP doesn't support IPv6, which results in huge delays
- Edit /etc/ssh/ssh_config
- Set AddressFamily to inet
- sudo service ssh restart - Restarts SSH service in Ubuntu