I must state first that I have like limited knowledge on the subject. So my opinion is based on generalities…
I would think that a dedicated device, with somewhere a clock device especially conceived for this, might be more precise than a computer that can do everything but has not dedicated circuits for this.
If you use your laptop at the maximum of its capacity (some Diva magic + Reaktor for instance) I would not be surprised that some sync computations are a bit late.