  This paper presents the first rotating leader state machine replication (SMR)
protocol that allows transactions to be confirmed in just a single round-trip
time in the Byzantine fault tolerance (BFT) setting. Based on minimal
alterations to the Internet Computer Consensus (ICC) protocol and with
negligible communication overhead, we introduce a novel dual mode mechanism
that enables optimal block finalization latency in the fast path. Crucially,
the modes of operation are integrated, such that even if the fast path is not
effective, no penalties are incurred. Moreover, our algorithm maintains the
core attributes of the original ICC protocol, including optimistic
responsiveness and rotating leaders without the necessity for a view-change
protocol.
  We prove the correctness of our Fast Internet Computer Consensus (FICC)
protocol and provide an open-source implementation of it. Both the FICC and
original ICC protocol are compared in a globally distributed wide-area network.
Our evaluation reveals that the FICC protocol achieves reduced latency compared
to the ICC protocol, without requiring additional security assumptions.
Furthermore, by increasing the number of replicas to $n = 5f + 1$, we exhibit
that latency improvements close to the theoretical maximum of 33% are
attainable. We conclude by highlighting the network topology as a significant
factor in evaluating and comparing the latency of consensus algorithms.
