I have code that I want to migrate from RecyclerView/XML style to composables. The original XML view is more complex than the example shown below, which has performance issues.

That original XML view is ConstraintLayout so initially I migrated it to the equivalent ConstraintLayout composable. I also tried Row/Column approach, too. Both versions can be found in the links below. The performance issue is expressed in slow scrolling - the initial scroll seems to freeze for a few seconds before moving just to the second item (in total I have 128 items). So I think there's also a problem with scroll speed too, that is, the amount of views which are scrolled with single finger gesture.

Compared to the RecyclerView approach, even when I do fast scrolling everything is smooth and a single scroll goes through a lot more items in total (arround 20-30 items).

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Setup information:
Jetpack compose 0.1.0-dev16
Phone: Nexus5X
Android 8.1 Oreo
Android Studio 4.2, latest Canary build

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Following a discussion on #compose channel in Slack, I'm posting relevant code:

https://gist.github.com/Rokata9/744b0ea614819fc51b7c85dfb90226b1 - This is the starting point for all composables. An activity with a view model, which retrieves list of items from a Firestore. After that it calls setContent to replace the view with the composable hierarchy.
https://gist.github.com/Rokata9/856bc5cdd25aa187a9e6783c747401b1 - The list based on LazyColumnFor

The item which is repeated, here are both ConstraintLayout and Row/Column versions:
ConstraintLayout - https://gist.github.com/Rokata9/f9252974343addc0fab2e2c93104382d
Row/Column - https://gist.github.com/Rokata9/197100002502a8490e2fe246811c6ec7

And the custom composables which are used (button and card image):
https://gist.github.com/Rokata9/a15913a33abd56f3cf69ff33cf088104 - A rounded image composable based on Card
https://gist.github.com/Rokata9/efec0fcfd8fc6dc02aa501e5f88a2f2b - A button which has an image and text next to it as its content, both items aligned with a Row

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In the attachments you can find the images uesd: no_avatar.png is used in the RoundedImage composable, whereas user.xml is used with the standard Image composable as vector resource.