Hi, When I insert an item into list displayed via `Column`all subsequent elements are recomposed, me...

# compose-desktop

[mcpiroman]

Hi,
When I insert an item into list displayed via `Column`all subsequent elements are recomposed, meaning that if I insert at the end everything's fine but when I insert at the beginning there is a huge delay.
Doesn't matter if I use `mutableStateOf`or mutableStateListOf, whether I use `key`function or not (though it does feel like it affects performance somewhat). I don't use `LazyColumn`because it is laggy in general.
Known problem, walkaround? Thanks.

[Dominaezzz]

Not fixes for that really. You asked Column to remeasure everything by inserting at the top. You'd need to use a LazyColumn if you want to skip recomposition of non-visible items.

[Dominaezzz]

How is it laggy?

[mcpiroman]

`LazyComunm`lags when scrolling (it is often ok with scrollwheel but not when dragging the scrollbar). But now that I switched my simplified testing example to `LazyColumn`I see that at least the performance of insertion is acceptable. I may have to try with maybe keys or something in my main case where it could took line a second to insert something.
FYI the list has about 300 items consisting of `Text`and Icon, it is just adapted tree view from CodeViewer example.

[mcpiroman]

But`Column`could eventually overcome that right? If the elements below do not change, they do not change height so they could be just shifted down without recomposition?

[Dominaezzz]

Nope, you need subcomposition to do that. Which Column doesn't do.

[Dominaezzz]

Yeah scrollbars are hard. You're saying your scrollbars aren't laggy on Column ?

[Dominaezzz]

Are the sizes of your items very different?

[mcpiroman]

All items are the same size, single line of text.
Yes, unlike on `LazyColumn`with `Columns`scrolling is smooth.