SceneManager.LoadSceneAsync causes lag spikes, how to make background loading less CPU heavy

Title says it all, recently upgraded to unity 5.3 for the new scene manager, the gist is im trying to load the levels in the background so i can have animations play during the changeover but SceneManager.LoadSceneAsync causes lag spikes and stuttering when first initiated, usually for less than a second but its quite noticeable, the method im using is to initiate loadlevelasync but set allowSceneActivation to false so it can be called when needed, does anyone have any tips or pointers on how to make this more efficient?

Maybe this helps?