I have an ascx-control is being placed 7 times at the aspx-page.
All controls render the same huge amount of rows: 2400.
The 1st control takes ~1 sec to render.
The 2nd - ~3 sec.
The 3rd - ~15 sec.
The 4th - ~25 sec.
The 5th - ~40 sec.
The 6th - ~65 sec.
The 7th - ~105 sec.
To render all controls on client it takes about 6 min, regardless the first 2 controls is being rendered almost immediately.
This is reproduced only on the Google Chrome the latest version (83.0.4103.97).
I did a try on the Chrome v.81, and there is no performance issue.
Also, there is no performance issue on the following browsers: Mozilla Firefox, IE 11, Edge.
Please see below usage of the RadListBox:
And set items at the ascx.cs:
DataTable list = GetList();
RadListBox1.DataSource = list;
Actually I have tried the Load On Demand feature, the controls have been loaded even immediately, but all custom js were failed.