RadHtmlChart with DateTime Axis Loads Slowly

AUTHOR: Richard Hellwege

DATE POSTED: May 18, 2018

PROBLEM

The RadHtmlChart performance suffers, or the browser hangs, when using a DateTime Axis with data-points in the same day.

DESCRIPTION

When I use a DateTime Axis, I sometimes see the RadHtmlChart load very slowly, or even cause the browser to hang. This seems to happen when there are data-points that are in the same day, but not when the data-points are more spread out.

SOLUTION

This issue occurs due to the way intervals are automatically generated for a DateTime Axis. The RadHtmlChart looks at the source data to calculate the interval between all data-points along the axis. For example, if the data contain two records that are 5-minutes apart, the data-points on the axis will have an interval of 5-minutes. If the data also contains records spanning a week, over 2,000 data-points would need to be generated along the DateTime Axis to show an unbiased representation of the data.

There are several options to overcome this behavior.

1. Explicitly set the BaseUnit property of the DateTime Axis to a value that will display the data correctly, without producing too many axis data-points.
   
   
2. Pre-process the source data before binding to the RadHtmlChart in order to aggregate values that are close together.
   
   
3. Remove the Time component from DateTime objects in the source data. This effectively makes the minimum interval one day.