[Dnssec-trigger] persistent cache needed?

[Chuck Anderson]

After booting up and re-opening Firefox, restoring 50-100 tabs causes
so much DNS traffic that unbound goes unresponsive, and queries
repeatedly timeout for many minutes until things finally settle down.
I thought Firefox's behavior was to not reload every tab until you
activate the tab, but maybe it is still doing DNS pre-fetches for the
inactive tabs?  I don't know.

I think we need a persistent cache, saved across restarts/reboots.
What else can we do to solve this problem?

Or is the verbosity the cause of the problem:

#journalctl -b -u unbound | wc -l
24581

unbound.conf:

server:
        # verbosity number, 0 is least verbose. 1 is default.
        verbosity: 3