Pi5: High CPU Usage on node deploy

[sincze]

I am using this great solution i.c.m Homeassistant running in a docker.
When I try to deploy:

The CPU usage instantly rises to 100%.

How would this be possible? I checked both on a Pi 4 8GB and a Pi 5 8GB. But same scenario same results.
According to HA I have over 400 Devices and nearly 6000 entities.

It seems that if the CPU reaches 100% there is a small delay in for example turning on lights... Kind of a bummer.

Any suggestions are appreciated.

[zachowj]

Things to try:

• Check the Node-RED logs for disconnecting/reconnecting messages.
• Disable all flows and deploy. Does CPU usage remain high?
• Disable the Home Assistant server config and deploy. Does CPU usage remain high?
• Remove the Home Assistant node package and restart. Does CPU usage remain high?

[sincze]

Thank you very much for trying to help me out.
Actions:

• First I started with a new Node Red installation with 0 flows.
• Expected Result: CPU usage low
• Result CPU usage is low.

• Create a flow with 3 nodes inject - change node to set a value to payload - debug node (Deployed)
• Expected Result: CPU usage low
• Result CPU usage is low.

- Imported the node-red-contrib-home-assistant-websocket to the palette. + running first flow

• Expected Result: CPU usage low
• Result CPU usage is low.

- Removed the function node and replaced it with a status node from the node-red-contrib-home-assistant-websocket (configured the node first to talk to my HA machine and Deployed)

• Expected Result: CPU usage low
• Result CPU usage is HIGH!

- Disabled the complete new flow (so no running flows) (Deployed)

• Expected Result: CPU usage low
• Result CPU usage is still HIGH!

- docker stop node-red stops the node-red docker container

• Expected Result: CPU usage low
• Result CPU usage is still low

- docker start node-red starts the node-red docker container

• Expected Result: CPU usage low
• Result CPU usage is HIGH

Check the Node-RED logs for disconnecting/reconnecting messages.

Checked the logs in Node-Red but they are pretty clean

Welcome to Node-RED
===================

26 Feb 17:20:24 - [info] Node-RED version: v4.0.9
26 Feb 17:20:24 - [info] Node.js  version: v22.14.0
26 Feb 17:20:24 - [info] Linux 5.10.103-v7l+ arm LE
26 Feb 17:20:25 - [info] Loading palette nodes
26 Feb 17:20:29 - [info] node-red-contrib-telegrambot version: v16.2.0
26 Feb 17:20:29 - [info] node-red-contrib-home-assistant-websocket v0.75.0 nodes initialized
26 Feb 17:20:30 - [info] Settings file  : /data/settings.js
26 Feb 17:20:30 - [info] Context store  : 'default' [module=localfilesystem]
26 Feb 17:20:30 - [info] User directory : /data
26 Feb 17:20:30 - [warn] Projects disabled : editorTheme.projects.enabled=false
26 Feb 17:20:30 - [info] Flows file     : /data/flows.json
26 Feb 17:20:30 - [info] Server now running at http://127.0.0.1:1880/
26 Feb 17:20:30 - [warn]

26 Feb 17:20:30 - [info] Starting flows
26 Feb 17:20:30 - [info] Started flows
26 Feb 17:20:30 - [info] [server:Home Assistant (SSL)] Connecting to https://myhost.local.nl
26 Feb 17:20:30 - [info] [server:Home Assistant (SSL)] Connected to https://myhost.local.nl

Disable all flows and deploy. Does CPU usage remain high?

• Yes

Disable the Home Assistant server config and deploy. Does CPU usage remain high?

• I did not understand this, my apologies

Remove the Home Assistant node package and restart. Does CPU usage remain high?
I removed node-red-contrib-home-assistant-websocket as a result

• CPU usage drops instantly.

Any suggestions are welcome.
I'll also try to setup a complete new HA install as well on a complete separate machine to see what is going to happen.

[zachowj]

Can you post your diagnostics information?

https://zachowj.github.io/node-red-contrib-home-assistant-websocket/guide/diagnostics.html

[sincze]

Would this be helpfull ??

Version: 0.75.0

Home Assistant version: 2025.2.4
Companion version: 0.0.0

Node-RED version: 4.0.9
Docker: yes
Add-on: no

Node.js version: v22.14.0 arm64 linux
OS: Linux 6.6.62+rpt-rpi-2712 arm64

[sincze]

I think I found at least something. Next to Home assistant i also have Domoticz running.

If I disable this one. Node-Red CPU usage drops to 17%
If I enable it again Node-Red spikes back to 100%

If I modify the settings to:

Messages are published differently however CPU stays low.

No clue what the relation is with node-red-contrib-home-assistant-websocket but at least we can see something changing.

Visible that I am switching something off and back on,.

[sincze]

According to the old 40 ;-)

For low CPU usage while maintaining usability in Home Assistant, Node-RED, and Domoticz using MQTT, here’s what I recommend:

Best MQTT Topic Structure for Domoticz → Home Assistant / Node-RED
✅ Use "Index" or "Name"

"Index" (domoticz/out/{idx}) → Best for direct integration with Home Assistant / Node-RED. Low CPU impact.
"Name" (domoticz/out/{name}) → Easier to read, but slightly higher CPU usage than "Index".
Avoid High CPU Options
🚫 Flat (domoticz/out) – Can cause high CPU usage because all messages are published under one topic.
🚫 Hierarchical (domoticz/out/{floor}/{room}) – More structured but increases CPU load.
🚫 Combined – Uses both Flat and Hierarchical, leading to even higher CPU usage.

Why "Index" or "Name" is Best?

• Lower CPU usage compared to Flat/Hierarchical/Combined.
• Easier to filter and use in Home Assistant and Node-RED automations.
• More structured and reduces unnecessary MQTT message traffic.

Extra Optimization:

• Enable "Retain" only if needed (e.g., for persistent sensor states).
• Use QoS 0 or 1 for efficient message delivery (QoS 2 adds overhead).
• Ensure Domoticz only publishes necessary devices via MQTT.

Final Recommendation:
✅ Use Index (domoticz/out/{idx}) for lowest CPU and best performance.
🔥 If you want more human-readable topics, use Name (domoticz/out/{name}) instead.