Bind-9.3.0 also appears to suffer from this bug, 9.2.3 works fine.
According to the discussion it appears it will be fixed in bind-9.4.0?
From: Justin Piszcz
This bug is present in Debian Sarge (Testing):
Basically, there is a 4-6 timeout when you use a caching DNS with bind 9.2.4 due to it trying to lookup ipv6 records.
Fix = use a later version or go back to 9.2.3, has this bug been reported to the
Debian bind maintainers?