'very slow' >> no
slower >> yes (but it may not be a delay, it may be the work on animation otherwise delay = 10% of global = add 4 days for release)
If there is an animation, it's not just to open a door, or play the guitar (I hope) ... what intrigues me is that it happens to only a third of renderings.
Is it possible that Sophia seeing Sam playing, leaves him alone a moment and goes elsewhere in the house (bathroom, kitchen, ...) ?
She could see Amber in the shower, or being offered an ice cube by Julia