Is IPv6 Faster Than IPv4? Often I see someone claim that IPv6 is faster than IPv4, or vice versa. The funny thing is that most of these discussions focus on NAT, protocol overhead, or header sizes, while the biggest source of performance difference is often something entirely different: routing. Let's assume you're sitting in Mumbai and connecting to a server in Frankfurt. Your IPv4 packets might leave through one provider, traverse a particular set of peers and transit networks, and arrive in Frankfurt through one route. Your IPv6 packets may take a completely different journey. - Different providers. - Different peering agreements. - Different congestion levels. - Different failures. - Different economics. Then someone runs a benchmark, sees IPv6 win by 20ms, and concludes that IPv6 is faster. But was it really the protocol? Or did it simply get a better path? This is where things become interesting. People often bring up NAT. Twenty years ago that may have been a more compelling argument. Today, modern networking hardware can NAT traffic at line rate without breaking a sweat. For most workloads, NAT is rarely the thing ruining your day. Others point to IPv6's larger header size. This is technically true. An IPv6 header is typically 20 bytes larger than an IPv4 header. On a standard 1500 bytes MTU, that works out to roughly 1.3% additional overhead. Meanwhile your packets are busy traversing ISPs/IXPs, transit providers, peering networks, congested links, overloaded routers, and occasionally what appears to be a routing decision made by an angry wizard. The extra 20 bytes are rarely the interesting part. The route usually is. The Internet is not one network. It's thousands of independently operated networks, each optimizing for their own economics, policies, capacity constraints, and business relationships. IPv4 and IPv6 often traverse that ecosystem differently. And that difference can easily dominate any protocol level overhead. This is also why mechanisms such as Happy Eyeballs exist. At some point the industry collectively realized that predicting whether IPv4 or IPv6 will perform better is often harder than simply trying both and using whichever works best.A surprisingly practical solution. So when someone asks whether IPv6 is faster than IPv4, my answer is usually: Sometimes. And sometimes IPv4 is faster than IPv6. More often than not, you're measuring a routing difference and attributing it to a protocol difference. Most people are comparing protocols. The packets are comparing paths. 🖖