I suspect the issue I’m going to describe below is my own fault.
When sending large amounts of rows 1000 to a WebListBox and specifying a cell style for each cell both Firefox and Edge hang, Edge being the worst it hangs for minutes and Firefox keeps bring up warning messages. Chrome and Safari including iOS seem to handle it fine. Without cell style it’s Edge and Firefox are fine.
Sample project https://dl.dropboxusercontent.com/u/76235150/Xojo/ExampleListBox.xojo_binary_project
You should know that the entirety of the WebListBox will be in the page sent to the browser. 1000 rows is a lot of data.
Unless you absolutely need all those 1000 rows displayed, you may want to explore smaller quantities of data at once, or better, separate data storage and presentation, for instance by storing data into an array, and only displaying part of it.
Assumed as much, just surprised by how badly edge and Firefox handle it compared to Safari and Chrome.