What takes time in clearing is not information transmission. Most of the time is spent managing risk. Sure, that includes persistence, but that is also margina

What takes time in clearing is not information transmission. Most of the time is spent managing risk. Sure, that includes persistence, but that is also marginal. You also have to validate integrity, authenticity, cross-reference against legal requirements (eg. enforce rates, detect fraud — including internal fraud, apply sanctions lists, estimate AML-CFT risk, …). You have to make sure all accounting rules are followed. You have to abide by the procedures that you and the regulator determined. All that with no downtime. All of this takes time. Historically, a large part was manual. While automation has helped, there are quite a few clearing houses where an army of programmers is spent battling the chaos. A system least tolerant to inconsistencies and most tolerant to failure, increases reliability while reducing risk. The cryptographic properties of a distributed blockchain help there, regardless of whether the system has open membership (which is not Facebook’s case, unlike most cryptocurrencies). A different ledger design can be equally powerful or more. In fact, I expect that a lot of the compliance and accounting logic can be expressed elegantly in a custom design.