I tried to set dropDown.dataSource to an array of objects rather than creating new smart-list-items. This improves performance a bit (it only needs about 300 ms), but it’s still relatively slow.

let perfStart = performance.now();
let dropDown = new window.Smart.DropDownList();
let datas = [];
for (let i = 0; i < 120; i++)
datas.push({
label: "Item " + i,
value: i
});
dropDown.dataSource = datas;
document.body.appendChild(dropDown);
let time = performance.now() - perfStart;
alert("Time: " + Math.floor(time));

Hi Peter,
thank you for your help!
By setting virtualized=true and setting itemHeight to a fixed value (e.g. 25), the performance is now better, it needs about 50-60 ms to create instead of 300 ms. Still, when I have multiple drop down lists, the delay is noticeable, e.g. when I have 4 smart-drop-down-lists to be shown on the page/window, they still need about 200-250 ms to create. This is still slower than using the jqxDropDownList widget.
I also tried to use a smart-input with setting readonly=true and dropDownButtonPosition=’right’, and using a datasource to show items like in the drop-down-list, which seems to be much faster than the smart-drop-down-list (only needs about 10 ms).
However, with smart-input I cannot set a different value for each item – the smart-input only seems to use the “label” property from the data source.
Thank you

Hi Peter,
when I combine the “.virtualized = true” setting with “.dropDownAppendTo = document.body”, (because I display it in a SmartWindow), then it seems the drop down list doesn’t work correctly in Firefox 78.0.2, whereas it works in Chrome. See the following code pen: https://codepen.io/KP-Traeger12/pen/OJMoMmK
In Firefox, it will look like this (only the first item is visible):