Exponential Editor Slate Performance Cost When Editing An Asset With Nested Instanced Structs

UDN Issue: [Link Removed]

• Create a C++ file in a chosen project (I used CitySample)
• Paste something like the following in it:
  ```
  // Copyright Epic Games, Inc. All Rights Reserved.

#pragma once

#include "CoreMinimal.h"
#include "InstancedStruct.h"
#include "Engine/DataAsset.h"
#include "LoganTestDataAsset.generated.h"

/**

• */
  USTRUCT(DisplayName = "Test Data Asset")
  UCLASS()
  class CITYSAMPLE_API UTestDataAsset : public UDataAsset

  { GENERATED_BODY() UPROPERTY(EditAnywhere, meta = (BaseStruct = "/Script/CitySample.TestDataNode")) FInstancedStruct Child; }

  ;

USTRUCT(DisplayName = "Test Data Node")
struct CITYSAMPLE_API FTestDataNode

;
```

• Create a new DataAsset that derives from the custom UDataAsset above
• Open it in editor and start creating deeply nested tree of children

BEFORE: Framerate would become unusable after about 7-9 levels deep
AFTER: Framerate should be acceptable after 15-20 levels deep.

NOTE: This is a pretty large change which has the potential to affect all sorts of InstancedStruct editing. While I have done my best to do my own exploratory testing - QA exploratory testing would be appreciated to ensure instanced struct editing is functional.