Swine flu screening
Don't forget that due to the pig flu case that arrived into BNE last week, Australian Quarantine are doing extra checks for everyone, regardless of nationality. Although a lot of people aren't travelling because of it and the global recession of course.
During peak times, the extra controls mean extra queues... and additional delays.
Apart from returning kiwis, compared to SYD and MEL, BNE probably isn't as busy an airport though.