run the attached example add-multiple.zul
click the 4 buttons and profile/compare the render timings
the first 2 buttons take ~1.3 seconds to render/resize
the "workaround" buttons only take ~40ms
equal/equivalent render times, if possible
Currently only happens on chrome.
The listbox with many rows/columns is only added to highlight the performance drain, which gets worse in more complex UIs.
the components are added one by one, calling firesized after each component, leading to "Forced reflows"
Appending the components into an initially invisible component or as a batch with a common parent avoids the loop of "Forced reflows"