Kafka 'reassign-partitions' behavior if the replica does not catches up

I attempted bin/kafka-reassign-partitions.sh for the topics in my cluster. It was automatic reassignment of topics to new brokers.

Kafka duly initiated the partition reassignment. I believe kafka controller will do the new leader election once the re-assigned partitions are in sync.

However, in my case I realized that the new re-assigned partitions are not getting in sync at all. The in-rate in the existing partition is far more then the sync rate between earlier and newly reassigned partitions.

In this scenario, will kafka wait indefinitely for the newly assigned partition to become sync (which will never be).

Secondly what are the options to speed up the partition replica sync rate?

Running kafka 0.8.0

Regards,
Virendra