BIND 9.5.1b1 cache cleaning

[Prabhat Rana]

I have BIND 9.5.1b1 running on Solaris 10. I have set my max-cache-size to 2048M. How does BIND 9.5.1b1 cleans the cache?  I heard it doesn't use the cleaning-interval anymore with this version even if you specify it in the named.conf? So would it cause any issues with such a large cache when its cleaning time? Also if the cache becomes 2048M will it cause any other performance issues such as latency having to search a 2048M cache itself?
Thanks
Prabhat.