There have been two major changes in Chart.js that will dramatically improve performance in the upcoming 2.9.0 release. We're also adding a section to the documentation about options you can set to improve performance over the defaults. We're hoping to release soon, but there are a couple pending PRs we'd like to review first

Also, if you're interested in realtime charts, here's a related plugin I've seen: https://github.com/nagix/chartjs-plugin-streaming