I have a creative world with a fairly large railway system, and when my friends are connected using Multiplayer with Xbox, they experience severe stuttering and lag while riding on minecarts. Their screens would freeze for a couple of seconds, move for one second, freeze again, move again and so on and so forth. Strangely, the lag doesn't affect me, the host. The stuttering doesn't happen when we're playing in person using LAN though. I tried to see if the problem was only in that world, but apparently the same issue occured on every other one on my device, even new worlds. When I tried riding on their worlds, the stuttering persisted (for everyone, not just me), meaning the problem isn't just on my device. My and their networks have a download speed of around 12mbps, and we all live in the same city, so connection shouldn't be the problem.