Large serializable field in a MonoBehaviour causing poor performance in Inspector

I have asset bundles where I group 3d models with additional meta data. A key requirement is I need an image of each 3d model. The simplest solution I’ve found is to generate these images/snapshots in the Unity Editor using Editor APIs, and storing the result with the model.

So I have a couple classes that look like this (simplified here):

public class Model {
	[HideInInspector]	//Serialized, but not shown in inspector
	public byte[] texture;
	public GameObject model;

	public string name;
	public string description;

	public void GenerateTexture() { ... } //This is called with a custom Inspector

	public Texture2D Texture {
		get {...}	//Converts this.texture to an actual Texture2D
		set {...}	//Converts a Texture2D to a byte[]

public class ModelPack:MonoBehaviour {
	public List<Model> gameModels;

ModelPack(s) are stored in asset bundles which are then loaded at runtime.

This works perfectly, except one minor-ish problem: performance in the Unity Inspector is terrible. The Unity (Editor) profiler shows a large amount of garbage collection happening in every UI update causing the whole Unity UI to freeze and skip. For the longest time I thought there was an issue with the custom inspector I wrote for the ModelPack/Model classes, but even completely disabling that the performance issue remains. I’ve finally come to the conclusion that the problem seems to be the texture byte array. If I mark it as NonSerialized then performance is fine in the Inspector.

I suspect the problem is that it’s constantly getting/setting and serializing/deserializing the value of the whole object in the inspector, even though I have ensured the texture value itself isn’t changing unless the associated model is changed. Since the texture is rather large (megabytes in size) that could create quite a strain.

Does this make sense? Is there a recommended limit on how much data should be stored when serializing a Unity MonoBehaviour? Is the entire MonoBehaviour serialized in one go every time? Is there a way to filter out that one field, or will I have to find an alternate way of storing these large byte arrays such as saving them to files?

Storing any kind of array with very large amount of elements is always a problem. Unity have to Serialize and Deserialize each elements individually, and in the inspector it does this frequently. I would recommend you to convert the whole byte array into a single string so that its just a single serialization.
you can use this method to convert a byte array into a string System.Convert.ToBase64String and use System.Convert.FromBase64String to convert the string back to byte array. This way the serialization load can be reduced.