Big data - the page gets stuck when scrolling


In my case, there are hundreds of thousands of tasks, and we also split tasks in row. so it may contains 4000+ tasks in one row.
the page gets really stuck when scrolling.
Also, we tired to achieve the same effect as virtual scrolling - load data in visible area dynamically when scroll
but it didn’t work.
is there any way to improve the performance such as virtual scrolling? Thank you.



I’m afraid there might be no good solution for your usage scenario.
We did a performance testing of dhtmlxGantt some time ago (results will be published in upcoming weeks), but there we stopped at 100k tasks per gantt. We didn’t continue the test further since gantt became too slow.

If you can send us some test data that represents the structure and size of datasets you use we can run some tests locally and look for possible optimizations.
I can’t promise any results, but we’ll keep you posted if we find something promising.


It is known bug with the split tasks. Even if the smart rendering is enabled (it is by default), Gantt still renders split tasks when they are outside the viewport.
The dev team will fix the bug in the future, but I cannot give you any ETA. Unfortunately, there is no workaround for that.



Thank you for your kind reply. I’m so sorry that I can’t send you some test data as it’s a large project.

Since Gantt renders split tasks when they are outside the viewport at present. I’m wondering if we can do something such as virtual scrolling to improve the performance base on the situation now. However, we have already tried, but it didn’t work.
So could you give us some implementable advice if Gantt can support virtual scrolling or lazy load.
Thank you so much.


Gantt already uses virtual scrolling with regular tasks, but for the split tasks, it is not working right now.
Here is the snippet, where you can reproduce the issue.
If you try scrolling Gantt horizontally, it works more or less smooth. So, there is no need to improve.
But if you scroll Gantt vertically, it will take more time, because Gantt renders all the split tasks on the row. At this point, there is no way to improve performance.

The future Gantt version (7.2) will have a way to filter split tasks via an event handler, and it should help adding a workaround.


Can you give us an approximate date about when will the Gantt version 7.2 can be released?
Thank you so much.


Unfortunately, I cannot give you any ETA. But I hope it will happen this summer.


It would be nice if it happens this summer. Wait for the good info. Thank you so much.