Laggy Lazy Column Android Compose

 I've created a whole app in Jetpack Compose. However, the performances on the Lazy Column are pretty bad and it does not make any sense. Lazy Column should be the substitution of RecyclerView, but RecyclerView works much better at the moment.

I made a Lazy Column with headers and Lazy Rows as items (basically a nested list). As you can see there are images but I used the Coil library so everything should be loaded in a separate thread. I've already seen these discussions: link1, link2. But it seems like there's not a solution to this problem, even though now Jetpack Compose is stable.

Did any of you find a way to get better performances or should I substitute this Lazy Rows with a RecyclerView?

Here's a screen of the page:

Solution-->

Things will speed up your Lazy List

If you're in debug mode, that's normal. Don't worry if your app is laggy in debugging. It's completely fine. Just create the APK in release mode (Build -> Generated Signed Bundle/APK), which might solve your problem. This happens because when in debugging, Compose translates bytecode in runtime using JIT. Make sure you're also using the R8 compiler in the release build. This is extremely important to improve general performance.

Set a key for your item. Initialize your Lazy list like this.

LazyColumn() {
    items(
        count = cartItems.size,
        key = {
            cartItems[it].cartItem.id
        },
        itemContent = { index ->
            val cartItemData = cartItems[index]
            CartItemWithActions(data = cartItemData)
            Divider(
                color = colorResource(id =R.color.separator_line)
            )
        }
    )
}

Setting a key works similar to the DiffUtil class in RecyclerView. Check the Maciej Przybylski's post.
Make sure every variable is using the remember{} block.

@Composable
fun MyComposable() {
    ...
    val wrongList = myViewModel.getList() // <- Don't do this
    val correctList = remember { myViewModel.getList() } // <- Do this
    ...
}

4. You can also use contentType, which defines the type of object in a list. This is useful if you have headers or different types of objects in your list. Learn more here.

5. Baseline Profiles. If you've tried everything but your list is still missing frames this might be it. In this talk, Rahul Ravikumar (Google engineer) reveals how Baseline Profiles improve performances up to 40%. What's this? Compose is a library and not native XML. This means that every time you execute your app, the code has to be translated at runtime. You can pre-execute and save all this code when installing the app using Baseline Profiles. Check this links: Baseline Profiles, Improving Performance with Baseline Profiles.

Check these resources never to have performance issues again. I highly suggest watching these videos: Optimizing Render Performance of Jetpack Compose, Performance best practices for Jetpack Compose, and reading this post.

Original Answer

SOLVED! Reading this reddit I found out the problem is only in the debug version. It seems crazy but it's true. That's because debug versions of Compose apps have a lot going on under the hood which impacts performance (pretty similar to what happens with Flutter). To solve the problem the only thing you need to do is to create a release version of your app. To do that, go to Build -> Generated Signed Bundle/APK. Create the key and then select release.

Enjoy your smooth app!