I don't know Laminar's official "policy" on this since XP 11 is so new, but I'm pretty sure it was 10 miles to keep your sim running smooth. But yes, it would be X-Plane dropping it, not us. That said, X-Plane 11 is still in its infancy and I would expect big improvements in the next weeks to month on the performance side, which should ultimately alleviate this.
Of course, none of this applies if you're actually using X-Plane 10. If that's the case then I'd be scratching my head.