With or without traffic data?
It could help potentially if you give a hint on your system, e.g. CPU, Ram and storage.
I expereience this on ALIX and APU1 systems but I expect it due to limited resources.
Intel(R) Xeon(R) CPU E5620 @ 2.40GHz
8 CPUs: 1 package(s) x 4 core(s) x 2 SMT threads
Load average 0.91, 0.66, 0.56
CPU usage 4%
Memory usage 16% of 6099 MiB
SWAP usage 0% of 16383 MiB
Disk usage ( / ) 1% of 117GiB - ufs
Disk usage ( /var/run ) 4% of 3.4MiB - ufs in RAM
I'm not using the Backup-package. I scp config.xml out every night by a (remote) cron job.
Thing I observed today: If I change a firewall rule it says on the top to hit the Apply button to activate the change. If I hit it right away, the wait incurs. If I wat for about 20 seconds and hit it, the applying is instant. It seems something goes on in the background that blocks certain processes.