> The purported performance hit wouldn't be from the propagation delay on any given router, but rather from shifts in traffic resulting in a longer path.
You are right, I neglected to point out that origin validation is (in the absence of shenanigans) not going to cause one path to be preferable to another: if the origin is the same AS, either both paths or neither is valid.
If the origin in two paths is two different ASes, either both are valid or shenanigans are afoot - perhaps there's a hijack being prevented, perhaps the network operator has screwed up their ROAs, perhaps the network operator is measuring sBGP uptake, perhaps the network operator is doing a rather bizarre and ineffectual form of traffic ingress management, or perhaps the network is in a transition from one AS to another, but those are all "shenanigans" in which routing efficiency is secondary to some other goal.
An alternative source for average BGP path length is https://blog.apnic.net/2024/01/10/bgp-in-2023-bgp-updates/ - where many other similar statistics can be found, and independently repeatable methodology is available. The average BGP path length for IPv4 is around 5.5 hops, and for IPv6 it is just shy of 5 hops. These numbers have been stable for a while with IPv4 slowly shrinking and IPv6 slowly growing, albeit in both cases by around 0.2 hops a decade.
And perhaps also relevant to the parent's question: path length itself is a pretty poor indicator of network performance by just about any measure you can name (excepting perhaps the TTL field), and is a last resort measure used only when all else is equal. The case of a prefix hijack being thwarted by origin validation is an extreme example in which the shorter (invalid) path represents 100% packet loss and the longer (valid) path given preference due to origin validation is infinitely more performant.
edit: oh, disclaimer - I am a co-author of one of the RPKI RFCs, and while I am personally not involved in secure BGP at present my employer definitely is. Opinions presented are mine.
