That seems a little over the top since you only have a few hundred pixels across the screen, which means you have several tens of times more samples than you need.
I would start by dramatically reducing the rate at which data is added to the chart.
Are you running the browser on the Pi too? If so then what happens if you close and re-open the browser?
Also are you running the latest version of node-red and node-red-dashboard? If not then worth upgrading I think, if nothing else then just to eliminate that from the equation.
Copyright OpenJS Foundation and Node-RED contributors. All rights reserved. The OpenJS Foundation has registered trademarks and uses trademarks. For a list of trademarks of the OpenJS Foundation, please see our Trademark Policy and Trademark List. Trademarks and logos not indicated on the list of OpenJS Foundation trademarks are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.
The OpenJS Foundation | Terms of Use | Privacy Policy | OpenJS Foundation Bylaws | Trademark Policy | Trademark List | Cookie Policy