Located in London, I measured the RTT or round trip time to 574,691 random webservers and plotted the times on the globe.
Discovery was done with masscan, measurements using hping and plotting with an old Python script I've revived and enhanced.
This is part of the next writeup on my blog, with which I will be posting any of the code I've used.
I'm thinking its harder to get sub 15ms consistently maybe? Brussels, Amsterdam, Paris, expected lightspeed times of 1-2ms, in reality you'll get 10-20ms.
Global internet is optimized for global connectivity, I'm imagining resources are better spent optimizing the 50-200ms range than the 1-10ms.