SciChart is by far the most performant charting library for WPF applications and Javascript, with easy to customize plots and chart modifiers

SciChart was easy to integrate into my WPF application and is super performant. I use a 2D chart to display a histogram of a thermography image in real-time. Furthermore, there are a variety of charts with many customization options, so that any data can be presented clearly. Academic licenses are available for free and you always get a quick response from support.

Very high performance, have not been able to really find a competitor in regards to real-time charting. Also the team at SciChart offers great support and documentation, which has made it a charm to implement.