The origin of this map is described in slightly more detail in the original blog post.Errata / Disclaimer
Everything is an estimate. Rounding errors abound. Don't use this for anything but entertainment and curiosity. But you already know that.
Some data may be missing. There may be faster connections.
If you find issues, please let me know
and I'll do my best to fix them.
Thanks to cuicuit on reddit and
@yorksranter for pointing out missing data
for Paris and London!
Ireland and parts of Spain are not well represented due to missing data.