### 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)

MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
	ERR_FAIL_NULL_V(multimesh, Color());
	ERR_FAIL_INDEX_V(p_index, multimesh->instances, Color());
	ERR_FAIL_COND_V(!multimesh->uses_custom_data, Color());
	_multimesh_make_local(multimesh);
	Color c;
	{
		const float *r = multimesh->data_cache.ptr();
		const float *dataptr = r + p_index * multimesh->stride_cache + multimesh->custom_data_offset_cache;
		uint16_t raw_data[4];
		memcpy(raw_data, dataptr, 2 * 4);
		c.r = Math::half_to_float(raw_data[0]);
		c.g = Math::half_to_float(raw_data[1]);
		c.b = Math::half_to_float(raw_data[2]);
		c.a = Math::half_to_float(raw_data[3]);
	}
	return c;
}
void MeshStorage::multimesh_set_buffer(RID p_multimesh, const Vector<float> &p_buffer) {
	MultiMesh *multimesh = multimesh_owner.get_or_null(p_multimesh);
	ERR_FAIL_NULL(multimesh);
	if (multimesh->uses_colors || multimesh->uses_custom_data) {
		
		_multimesh_make_local(multimesh);
		uint32_t old_stride = multimesh->xform_format == RS::MULTIMESH_TRANSFORM_2D ? 8 : 12;
		old_stride += multimesh->uses_colors ? 4 : 0;
		old_stride += multimesh->uses_custom_data ? 4 : 0;
		ERR_FAIL_COND(p_buffer.size() != (multimesh->instances * (int)old_stride));
		multimesh->data_cache = p_buffer;
		float *w = multimesh->data_cache.ptrw();