That is using
bg-mining-enable=true
bg-mining-min-idle-interval=5 # seconds
bg-mining-idle-threshold=200 # average idle %
in /etc/monerod.conf instead of something like
[Service]
...
Nice=5
CPUSchedulingPolicy=idle
IOSchedulingClass=idle
in /etc/systemd/system/monerod.service?
The latter can better utilize all available idle CPU resources, but I can imagine it can become starved if all of regular CPU priority capacity is used by other parts of the system. Does it pose a problem for the daemon (that is used just as a local, mining service)?