Thank you for providing the Dojo.
The kendo widgets are already heavily optimized for speed. In your particular case a technology limit has been hit i.e. it is not possible to force the browser to render items/intervals faster than it is currently doing without reducing the amount of rendered items/intervals.
To answer your question - we suggest enabling paging on the grid as it seems that the bulk of rendering time is going into the grid rendering. If the performance with paging enabled is good enough you can avoid increasing the intervals in the chart.
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