Very high CPU usage after upgrading to 2026.9.0

The problem

Ever since upgrading to 2026.9.0, I have noticed that my server's CPU usage has been much higher than normal. I checked CPU usage on my server, and it is reporting the HAOS VM as the top CPU user by a wide margin. I installed the Glances add-on in HA, and it looks like the homeassistant container is continuously using very high CPU usage (close to 100% continuously). The top command is python3 -P -m homeassistant --config /config.

I am running HAOS on a TrueNAS CORE VM. It is assigned 4 CPU and 8gb RAM.

What version of Home Assistant Core has the issue?

2026.9.0

What was the last working version of Home Assistant Core?

2026.8.3

What type of installation are you running?

Home Assistant OS

Integration causing the issue

No response

Link to integration documentation on our website

No response

Diagnostics information

No response

Example YAML snippet

Anything in the logs that might be useful for us?

Logs are pretty quiet. Nothing I can see that is relevant.

Additional information

No response

Start by reproducing the continuous high CPU usage in the Home Assistant OS setup, comparing Core 2026.9.0 with the last working 2026.8.3. Profile the python3 -P -m homeassistant --config /config process and inspect the quiet logs to identify the regression. Done means the cause is isolated and the excessive CPU usage is resolved or covered by a regression test.