### Godot version

v4.2.beta1.official [b1371806a]

### System information

Ubuntu 22.04.3 LTS 22.04 - X11 - GLES3 (Compatibility) - AMD Radeon RX 560 Series (polaris11, LLVM 15.0.7, DRM 3.42, 5.15.0-88-generic) () - AMD Ryzen 3 1200 Quad-Core Processor (4 Threads)

### Issue description

![image](https://github.com/godotengine/godot/assets/1330325/7a986599-5a68-42a4-beb1-5d3b4bf7db6b)
![image](https://github.com/godotengine/godot/assets/1330325/e8b8546b-b47b-4add-9567-7f70709ab03c)

Culling 3D goes bellow 60 fps even with just about 50 simple animated models. With v4.2.dev6.official [57a6813bb] many more models can be spawned without fps drop. However, both versions do show high cpu usage for culling 3D. Without animations there's barely any usage.

### Steps to reproduce

Spawn models with animation with the Compatibility renderer.

### Minimal reproduction project

[CullMRP.zip](https://github.com/godotengine/godot/files/13400514/CullMRP.zip)

}
	if (multimesh->data_cache_dirty_regions) {
		memdelete_arr(multimesh->data_cache_dirty_regions);
		multimesh->data_cache_dirty_regions = nullptr;
		multimesh->data_cache_used_dirty_regions = 0;
	}
	
	
	int color_and_custom_strides = (p_use_colors || p_use_custom_data) ? 2 : 0;
	multimesh->instances = p_instances;
	multimesh->xform_format = p_transform_format;
	multimesh->uses_colors = p_use_colors;
	multimesh->color_offset_cache = p_transform_format == RS::MULTIMESH_TRANSFORM_2D ? 8 : 12;
	multimesh->uses_custom_data = p_use_custom_data;
	multimesh->custom_data_offset_cache = multimesh->color_offset_cache + color_and_custom_strides;
	multimesh->stride_cache = multimesh->custom_data_offset_cache + color_and_custom_strides;
	multimesh->buffer_set = false;
	multimesh->data_cache = Vector<float>();
	multimesh->aabb = AABB();
	multimesh->aabb_dirty = false;
	multimesh->visible_instances = MIN(multimesh->visible_instances, multimesh->instances);
	if (multimesh->instances) {
		glGenBuffers(1, &multimesh->buffer);
		glBindBuffer(GL_ARRAY_BUFFER, multimesh->buffer);
		GLES3::Utilities::get_singleton()->buffer_allocate_data(GL_ARRAY_BUFFER, multimesh->buffer, multimesh->instances * multimesh->stride_cache * sizeof(float), nullptr, GL_STATIC_DRAW, "MultiMesh buffer");
		glBindBuffer(GL_ARRAY_BUFFER, 0);
	}
	multimesh->dependency.changed_notify(Dependency::DEPENDENCY_CHANGED_MULTIMESH);
}
int MeshStorage::multimesh_get_instance_count(RID p_multimesh) const {