With the same and constant height, the list builder can more easily calculate when the item should render outside of the viewport. If your list items are all different heights, you make it hard for the list builder to work properly. Even if there is no performance issue now, as a list item, it's very easy to cause problems with seemingly innocuous code, because that code is potentially getting repeated hundreds to thousands of times. Not only that, but as an item in a list, performance needs to be considered. I would argue that if your list item has grown enough to warrant even thinking about extracting parts of it, you would probably have or should have a good name for it. But you still got a good point of course. I would like to experiment using a cache. It just seems when I scroll long list (1000 items) using a mouse in desktop app, Flutter is recalculating sizes of many items which can be slow, just to find the visible items. Not sure exactly how Flutter works withs regards to that, but I always intended to find out. If the content of the list items never change it seems even better performance-wise to keep a cache of the (widget) items if not too many, then Flutter can reuse the layouting/renderobjects of the list items after reordering. Lets say the user changes order of that list, then I guess the list item widgets need to be rebuilt, even using dedicated item widgets. But to create some widgets for parts of that item in name of optimization seems a little stretch if there is no performance problem, naming those widgets could be little awkward. Naturally it makes sense to create a widget that are easy to name and recognize, like some item in a list.

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