May be if you send us a project that we can actually run and test we can give you a more constructive suggestion towards increasing the chart's performance. I would usually suggest to decrease the number of the total data points. Right now you have 3 series with 200 data points each (600 in total). Try decreasing the total number of data points to 200.
Additionally you can switch to the RadChartView
, which is a newer control with a higher performance rate and is generally more flexible than the RadChart. Note that these are two different controls and they do not have an equivalent for each feature.
the Telerik team