IPv6 is the most recent version of the Internet Protocol (IP), which can solve the problem of IPv4 address exhaustion and allow the growth of the Internet (particularly in the era of the Internet of Things). IPv6 networks have been deployed for more than a decade, and the deployment is still growing every year. This empirical study was conducted from the perspective of end users to evaluate IPv6 and IPv4 performance by sending probing traffic to 1792 dual-stack sites around the world. Connectivity, packet loss, hop count, round-trip time (RTT), and throughput were used as performance metrics. The results show that, compared with IPv4, IPv6 has better connectivity, lower packet loss, and similar hop count. However, compared with IPv4, it has higher latency and lower throughput. We compared our results with previous studies conducted in 2004, 2007, and 2014 to investigate the improvement of IPv6 networks. The results of the past 16 years have shown that the connectivity of IPv6 has increased by 1–4%, and the IPv6 RTT (194.85 ms) has been greatly reduced, but it is still longer than IPv4 (163.72 ms). The throughput of IPv6 is still lower than that of IPv4.