Replication: re-initialisation of failed master

We run a 2 node setup replicating between a master and synchronous slave, currently when we want to failover we basically kill the master off, create a recovery file and re-point the traffic via a DNS record etc, we're looking at implementing a corosync/pacemaker setup shortly.

Once we're running with the old secondary as the master the only way we have to re-stage the old master is to use pg_basebackup against the new master to replace the previous master's data directory.

It feels that given how little has probably changed on the new master versus the old master that there should be a faster way of re-initializing the old master as a slave. Is there some sort of short-cut speedup I'm missing here? I suppose I'm mainly curious as to what techniques most admins use to accomplish this!

Thanks in advance

Rob