IXFR and Notify speed

[Robert Messinger]

I have NS records for all of the nameservers.
All namservers are 9.2.2rc1 or 9.2.1

The master nameserver has: (even tough it's on by default)
provide-ixfr yes;

The slave nameserver has: (even though it's on by default)
request-ixfr yes;

Yet, it is taking very long for the slave servers to be updated.
Is there something else that needs to be done or is this a bug?

Thanks for any help.