CPU/Load issues (FreeBSD, BIND 9.4.1)

[John Wobus]

I don't have FreeBSD experience, but I do have experience
with a bind instance that hits a wall after some time.

One good thing to look at is how much memory bind is using.
Conceivably, adding memory could solve your problem.
The size of your cache depends upon the pattern of your
clients' usage.  If that is, say, 20% more than your actual
memory, then it is easy to imagine the server runs fine
for a while, while the cache builds, but eventually the
server spends processor time thrashing.

John Wobus