Gantt interactivity lag with large task sets when autosize is true

Gantt
#1

I am experiencing significant performance issues in DHTMLX Gantt when working with large datasets.

Specifically, when the number of tasks exceeds ~1000 and gantt.config.autosize = true is enabled, the overall interactivity of the Gantt chart degrades noticeably.

Observed behaviour:

I am experiencing a laggy behaviour when:

  • Expanding and collapsing parent/project tasks
  • Resizing columns
  • Zooming in and out

Reproducible example:

I have created a minimal example demonstrating the issue here

Question:

  • Is this a known limitation when using autosize with large datasets?
  • Are there recommended optimizations or alternative configurations to improve performance in this scenario?

Any guidance or best practices for handling large-scale Gantt charts would be appreciated.

#2

Hello @Mokgadi_Mabapa,

This is an expected behaviour. When the autosize config is enabled, Gantt stretches its container to fit the sizes of all task rows, and it renders the HTML elements of all tasks. This can affect performance.

Regarding performance tweaks and best practices for handling large datasets in Gantt:

Gantt performance depends on the number of loaded tasks and the enabled features. We have the following article with the performance comparison depending on the enabled features:

You can also test it manually by using the snippets in the article and the following sample:

https://docs.dhtmlx.com/gantt/samples/?sample='08_api/10_performance_tweaks.html'&filter=''

Also, by default, DHTMLX Gantt uses smart rendering, which ensures that only visible tasks and links within the current viewport are rendered. This helps to improve performance with large datasets.

For more information on ways to improve performance, please check this article:

Here is a sample with 30000 tasks and 3671 links loaded within ~1 sec:

https://docs.dhtmlx.com/gantt/samples/?sample=‘02_extensions/13_smart_rendering.html’&filter=‘’

Best regards,
Valeria Ivashkevich
DHTMLX Support Engineer