Synchronization of servers in a replica set takes quite a while to
accomplish in normal circumstances, which is hurting for test suites
that go over the trouble of shutting down servers mid-way through,
and then have to wait for the replica set to stabilize again before
continuing to run.

Reducing this delay, even if it requires a flag and burning down the
CPU a bit more, will speed up the testing and development of drivers,
and consequently will also encourage better test suites to be
developed.

As a reference, there was an exchange in mongodb-dev about an year ago:

https://groups.google.com/forum/#!topic/mongodb-dev/EUQ2jyTzu-0