Unity officials really aren't working, you can be sure of that. Nobody is doing their job! Everyone is just trying to complete their day by filling up the working hours. You can never make any progress with such an ineffective team. Unity will never be the application of your dreams. I'm really angry, everything is going wrong, the same problems haven't been solved for years, the documentation is written carelessly, and the Unity boss insults the developers. I really hate you, Unity!

Not fixed - problem persists in Unity 2019.2.18

The problem is still there in Unity 2019.4.31f1

Still an issue in 2021.2.3

For anyone that uses addressables - we managed to fix this for us.

When using preview window an inspector header is redrawn and addressable entry deep check is performed. This causes GC.

private static List<AddressableAssetEntry> implicitEntriesBuffer = new List<AddressableAssetEntry>();
private static HashSet<string> processedPaths = new HashSet<string>();
private static HashSet<string> validPaths = new HashSet<string>();

internal AddressableAssetEntry GetImplicitEntry(string implicitAssetPath)
{
var path = AssetPath;
if (string.IsNullOrEmpty(path))
return null;

if (!processedPaths.Contains(path))
{
processedPaths.Add(path);
if (AssetDatabase.IsValidFolder(path))
validPaths.Add(path);
}

if (validPaths.Contains(path))
{
return GetFolderSubEntry(implicitAssetPath);
}
#pragma warning disable 0618
if (MainAssetType == typeof(AddressableAssetEntryCollection))
{
GatherAssetEntryCollectionEntries(implicitEntriesBuffer, null);
}
#pragma warning restore 0618

AddressableAssetEntry result = null;
for (int i = 0; i < implicitEntriesBuffer.Count; i++)
{
if (implicitEntriesBuffer[i].AssetPath == implicitAssetPath)
{
result = implicitEntriesBuffer[i];
break;
}
}
implicitEntriesBuffer.Clear();
return result;
}

It still does in Unity 2020.3 LTS

Still a problem in 2019.4.26f1

Still a problem in 2019.4.15f1

Still a problem in 2019.4.14f

The problem is still there in Unity 2019.3.3.f1