This IPv6 Land Speed Record documentation has some nice numbers:
In the same period and with almost the same setup (the distance was shorter, but the endstations were the same) also the TCP/IPv4 LSR was set. But IPv4 was better:
Distance: 10949 KM
Data transferred: 2.3 Terabytes
Average speed (over 60 minutes): 5.64 Gbps
Record submitted: 61,752,360,000,000,000 meters-bits/sec
Distance: 11539 km
Data transferred: 560 Gbytes
Average speed (over 20 minutes): 4.00 Gbps
Record submitted: 46,156,000,000,000,000 meters-bits/sec
But I would assume, globally, the result may be different due to the IPv6 jumbograms:
IPv4 limits packets to 65535 (216−1) octets of payload. An IPv6 node can optionally handle packets over this limit, referred to as jumbograms, which can be as large as 4294967295 (232−1) octets.
So, even though the address is longer, the payload is much bigger.