PropagateSelected becoming slow when adding lot's of items to a dropdown in multiple batches

[koenvd]

Description

When adding items to a dropdown in mulitple batches the propagateSelected method takes considerable time to run and becomes slower with a higher number of items.

To reproduce create a dropdown and add items to the dropdown in batches. Amount of items something like 100, 200, 300, ... When you check the performance you will notice the propagateSelected taking more and more time to execute. The reason for this is that the propagateSelected method does a loop for every item in the oldItems list over the complete list of the newItems which makes this a O(n^2) algorithm.

There are different ways to improve this:

• Only match selected items would solve my use case since typically the amount of selected items is a lot lower than the total amount of items.
• Ideally we would like to do a fast lookup in a Dictionary based on a lookup key (eg the stringified object). But this doesn't look straightforward because matching items is currently being done on a substring of the stringified object. However I don't get why this is done. Maybe someone can explain the reasoning of this? If we could drop this substring requirement a very fast lookup in a Dictionary would become possible.

Carbon Design System: 5.26.0

[github-actions]

🎉 This issue has been resolved in version 5.28.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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