### Current Behavior
If messages passed to the ui-chart node include significanā¦t amounts of additional data then the node red process uses an increasing amount of CPU time as the number of data points on the chart increases.
For the example flow below, running node-red on an Intel i7, initially node-red shows about 2% usage. The flow injects a message each second, and over about 20 mins the CPU slowly increases to around 8%. Stopping the incoming messages immediately drops the CPU usage back to 2%, and releasing them again switches it back to 8%. Obviously, using 6% of an i7 core on just buffering up messages is ridiculous.
It is not a browser related issue as the symptom can be seen even if there is no browser open.
The fact that it increases slowly means that it not to do with rolling the message buffer as it is not necessary for the buffer to be full.
The message is significant but not huge, this is the function generating it
```
msg = {
"payload": -433,
"topic": "M3 (Measured)",
"mac": "3C1ACCBAA19D",
"data_type": "int16",
"property": "battery_power",
"communication_status": "operational",
"scale": 1,
"unit": "W",
"precision": 1,
"friendly_name": "Battery Power",
"device_class": "power",
"state_class": "measurement",
"entry_type": "SENSOR_DEFINITIONS",
"_msgid": "16df34e86e841df2",
"messageId": "6a3d7abd40cb157a90acc984",
"modbusRequest": {
"unitid": 1,
"fc": 3,
"address": 30001,
"quantity": 1,
"emptyMsgOnFail": true,
"keepMsgProperties": true,
"enableDeformedMessages": false,
"messageId": "6a3d7abd40cb157a90acc984"
},
"responseBuffer": {
"data": [
65103
],
"buffer": [
254,
79
]
},
"parse_buffer": [
254,
79
],
"specification": {
"options": {
"byteSwap": false,
"resultType": "keyvalue",
"singleResult": true,
"msgProperty": "translated_payload",
"setTopic": true
},
"items": [
{
"name": "value",
"type": "int16be",
"offset": 0,
"length": 1,
"mask": "",
"scale": "1",
"offsetbit": 0,
"id": 0,
"value": -433
}
]
},
"originalPayload": [
65103
],
"values": [
-433
],
"objectResults": {
"value": {
"name": "value",
"type": "int16be",
"offset": 0,
"length": 1,
"mask": "",
"scale": "1",
"offsetbit": 0,
"id": 0,
"value": -433
}
},
"keyvalues": {
"value": -433
},
"arrayResults": [
{
"name": "value",
"type": "int16be",
"offset": 0,
"length": 1,
"mask": "",
"scale": "1",
"offsetbit": 0,
"id": 0,
"value": -433
}
],
"buffer": [
254,
79
],
"translated_payload": {
"value": -433
},
"_event": "node:53ebc095797a50fc"
}
msg.payload = Math.floor(Math.random() * (2000 - (-1000) + 1)) + (-1000);
return msg;
```
Adding a node in front of the chart which moves just the payload and topic into a new message and passing that to the chart stops the issue from occurring.
The problem was identified by a user in forum post https://discourse.nodered.org/t/feasability-of-migrating-to-dashboard-2-0/101298.
I am investigating to find which part of the code is using up the CPU.
### Expected Behavior
_No response_
### Steps To Reproduce
Run this flow and watch the node-red CPU usage over about 20 minutes.
```
[{"id":"c12532a704294d5c","type":"group","z":"997da33a0beedade","name":"Chart CPU test. Issue #2151","style":{"label":true},"nodes":["893419d21d52a0f3","392c75611b71aaa9","1a80648df0d6abfd"],"x":74,"y":4659,"w":692,"h":82},{"id":"893419d21d52a0f3","type":"inject","z":"997da33a0beedade","g":"c12532a704294d5c","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"1","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"","payloadType":"date","x":190,"y":4700,"wires":[["392c75611b71aaa9"]]},{"id":"392c75611b71aaa9","type":"function","z":"997da33a0beedade","g":"c12532a704294d5c","name":"Create object","func":"msg = {\n \"payload\": -433,\n \"topic\": \"M3 (Measured)\",\n \"mac\": \"3C1ACCBAA19D\",\n \"data_type\": \"int16\",\n \"property\": \"battery_power\",\n \"communication_status\": \"operational\",\n \"scale\": 1,\n \"unit\": \"W\",\n \"precision\": 1,\n \"friendly_name\": \"Battery Power\",\n \"device_class\": \"power\",\n \"state_class\": \"measurement\",\n \"entry_type\": \"SENSOR_DEFINITIONS\",\n \"_msgid\": \"16df34e86e841df2\",\n \"messageId\": \"6a3d7abd40cb157a90acc984\",\n \"modbusRequest\": {\n \"unitid\": 1,\n \"fc\": 3,\n \"address\": 30001,\n \"quantity\": 1,\n \"emptyMsgOnFail\": true,\n \"keepMsgProperties\": true,\n \"enableDeformedMessages\": false,\n \"messageId\": \"6a3d7abd40cb157a90acc984\"\n },\n \"responseBuffer\": {\n \"data\": [\n 65103\n ],\n \"buffer\": [\n 254,\n 79\n ]\n },\n \"parse_buffer\": [\n 254,\n 79\n ],\n \"specification\": {\n \"options\": {\n \"byteSwap\": false,\n \"resultType\": \"keyvalue\",\n \"singleResult\": true,\n \"msgProperty\": \"translated_payload\",\n \"setTopic\": true\n },\n \"items\": [\n {\n \"name\": \"value\",\n \"type\": \"int16be\",\n \"offset\": 0,\n \"length\": 1,\n \"mask\": \"\",\n \"scale\": \"1\",\n \"offsetbit\": 0,\n \"id\": 0,\n \"value\": -433\n }\n ]\n },\n \"originalPayload\": [\n 65103\n ],\n \"values\": [\n -433\n ],\n \"objectResults\": {\n \"value\": {\n \"name\": \"value\",\n \"type\": \"int16be\",\n \"offset\": 0,\n \"length\": 1,\n \"mask\": \"\",\n \"scale\": \"1\",\n \"offsetbit\": 0,\n \"id\": 0,\n \"value\": -433\n }\n },\n \"keyvalues\": {\n \"value\": -433\n },\n \"arrayResults\": [\n {\n \"name\": \"value\",\n \"type\": \"int16be\",\n \"offset\": 0,\n \"length\": 1,\n \"mask\": \"\",\n \"scale\": \"1\",\n \"offsetbit\": 0,\n \"id\": 0,\n \"value\": -433\n }\n ],\n \"buffer\": [\n 254,\n 79\n ],\n \"translated_payload\": {\n \"value\": -433\n },\n \"_event\": \"node:53ebc095797a50fc\"\n}\nmsg.payload = Math.floor(Math.random() * (2000 - (-1000) + 1)) + (-1000); \nreturn msg;","outputs":1,"timeout":0,"noerr":0,"initialize":"","finalize":"","libs":[],"x":430,"y":4700,"wires":[["1a80648df0d6abfd"]]},{"id":"1a80648df0d6abfd","type":"ui-chart","z":"997da33a0beedade","g":"c12532a704294d5c","group":"4f87bd59a15b847e","name":"","label":"cpu test","order":9007199254740991,"chartType":"line","category":"topic","categoryType":"msg","xAxisLabel":"","xAxisProperty":"","xAxisPropertyType":"timestamp","xAxisType":"time","xAxisFormat":"","xAxisFormatType":"auto","xmin":"","xmax":"","yAxisLabel":"","yAxisProperty":"payload","yAxisPropertyType":"msg","ymin":"","ymax":"","bins":10,"action":"append","stackSeries":false,"pointShape":"circle","pointRadius":"1","showLegend":true,"removeOlder":1,"removeOlderUnit":"3600","removeOlderPoints":"","colors":["#0095ff","#ff0000","#ff7f0e","#2ca02c","#a347e1","#d62728","#ff9896","#9467bd","#c5b0d5"],"textColor":["#666666"],"textColorDefault":true,"gridColor":["#e5e5e5"],"gridColorDefault":true,"width":6,"height":8,"className":"","interpolation":"step","x":680,"y":4700,"wires":[[]]},{"id":"4f87bd59a15b847e","type":"ui-group","name":"test","page":"c6ff182a4185f2f2","width":"6","height":"1","order":1,"showTitle":true,"className":"","visible":"true","disabled":"false","groupType":"default"},{"id":"c6ff182a4185f2f2","type":"ui-page","name":"Test page","ui":"ID-BASE-1","path":"/testpage","icon":"home","layout":"grid","theme":"c4cba76c368d7996","breakpoints":[{"name":"Default","px":"0","cols":"3"},{"name":"Tablet","px":"576","cols":"6"},{"name":"Small Desktop","px":"768","cols":"9"},{"name":"Desktop","px":"1024","cols":"12"}],"order":10,"className":"","visible":true,"disabled":false},{"id":"ID-BASE-1","type":"ui-base","name":"Dashboard","path":"/dashboard","appIcon":"","includeClientData":true,"acceptsClientConfig":["ui-control","ui-notification"],"showPathInSidebar":false,"headerContent":"page","titleBarStyle":"default","showReconnectNotification":false,"notificationDisplayTime":"1","showDisconnectNotification":true,"allowInstall":true},{"id":"c4cba76c368d7996","type":"ui-theme","name":"Test theme","colors":{"surface":"#ffffff","primary":"#0094ce","bgPage":"#eeeeee","groupBg":"#ffffff","groupOutline":"#cccccc"},"sizes":{"density":"default","pagePadding":"12px","groupGap":"12px","groupBorderRadius":"4px","widgetGap":"12px"}},{"id":"02cfc10c5dadf085","type":"global-config","env":[],"modules":{"@flowfuse/node-red-dashboard":"1.30.2"}}]
```
### Environment
- Dashboard version: 1.30.2 (also checked with 1.28.0)
- Node-RED version: 5.0.0
- Node.js version: 24.18.0
- npm version:
- Platform/OS: Ubunto 26.04 on laptop
- Browser:
### Have you provided an initial effort estimate for this issue?
I am not a FlowFuse team member
