Depending on you configuration an Unbound reload can take a few seconds to a few minutes to complete, hence disruption DNS service to devices. Running cron update during off hours is recommended.
With the Live Reload, pfBlockerNG perform live Unbound conf modification without interrupting DNS service. So you can run Cron Update hourly.
Live reload still have an issue where the Unbound internal DB becomes out of sync with pfb_dnsbl.conf file. It shows in the pfblockerng.log as
Resolver Live Sync... completed [ 09/06/18 05:29:28 ]
DNSBL update [ 1107297 | PASSED ]... completed [ 09/06/18 05:29:29 ]
DNSBL DEBUG..[ Data(s): 1107298 Zone(s): 950371 | 09/06/18 05:29:52 ]
When this happens, you can run a Force Reload DNSBL to correct the drift. Or you can just perform a Unbound reload with the shell cmd :
unbound-control -c /var/unbound/unbound.conf reload
code
The widget DNSBL Unbound total queries counter might be cleared when an Unbound reload, giving you bad statistics. Simply clear the DNSBL counters by clicking on the Garbage Can icon in the widget.