Large subtest qty freezes some UI elements #21339
Description
Testing #21306
subtest with range (0, 10k) caused a number of UI elements to freeze while running, most apparent when resizing the window.
*note: all actions resolve and render properly immediately upon test completion
While the 10k subtests are running, the window cannot be closed nor reloaded. UI elements can be interacted with, but nothing happens other than visually showing that they were clicked upon.
ex: folders showing as expanded, but not showing contents
other graphical issues
