You are referring to the "load average", which is displayed in the web Admin GUI and is taken directly from the OS.
Here's a little background reading:
It is not unusual for the CPU on a low spec Pi (or any Pi, for that matter) to be fully utilized for short periods.
When you install Pi-hole, that uses a lot of CPU. Same for running apt upgrade
, rebuilding gravity, etc.
Unless the Pi is stuck on 1.4 load, you don't need to worry about this. CPU utilization changes over time.
Here is an example. This is a NanoPi NEO (mid spec SBC) running Armbian Bookworm.
Normally it sits on the shelf, doing its Pi-hole thing, with very little load:
nanopi-neo:~:# uptime
14:38:30 up 4 days, 23:38, 1 user, load average: 0.08, 0.02, 0.01
But, if I run a gravity update (and this Pi-hole only uses two lists, so there isn't a whole lot of work to update gravity) you see the load jump up as expected.
nanopi-neo:~:# pihole -g
[i] Neutrino emissions detected...
[✓] Pulling blocklist source list into range
[✓] Preparing new gravity database
[✓] Creating new gravity databases
[i] Using libz compression
[i] Target: https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
[✓] Status: Retrieval successful
[✓] Parsed 144648 exact domains and 0 ABP-style domains (ignored 1 non-domain entries)
Sample of non-domain entries:
- "0.0.0.0"
[i] List has been updated
[i] Target: https://www.github.developerdan.com/hosts/lists/ads-and-tracking-extended.txt
[✓] Status: Retrieval successful
[✓] Parsed 429230 exact domains and 0 ABP-style domains (ignored 0 non-domain entries)
[i] List has been updated
[✓] Building tree
[✓] Swapping databases
[✓] The old database remains available
[i] Number of gravity domains: 573878 (565421 unique domains)
[i] Number of exact blacklisted domains: 4
[i] Number of regex blacklist filters: 27
[i] Number of exact whitelisted domains: 36
[i] Number of regex whitelist filters: 0
[✓] Flushing DNS cache
[✓] Cleaning up stray matter
[✓] FTL is listening on port 53
[✓] UDP (IPv4)
[✓] TCP (IPv4)
[✓] UDP (IPv6)
[✓] TCP (IPv6)
[✓] Pi-hole blocking is enabled
nanopi-neo:~:# uptime
14:39:04 up 4 days, 23:39, 1 user, load average: 0.36, 0.09, 0.03
Then, fairly quickly over time, the load is reduced again and quickly goes back to the steady state value I normally see.
nanopi-neo:~:# uptime
14:39:18 up 4 days, 23:39, 1 user, load average: 0.28, 0.09, 0.03
nanopi-neo:~:# uptime
14:40:48 up 4 days, 23:41, 1 user, load average: 0.06, 0.06, 0.02