When you throw an arrow, an item or some potions they can lag in mid air if you have too much command blocks running in your world that it creates lag spikes or auto saving

Steps to reproduce:
1. Enter a world with some progress in It (with command blocks)
2. Go far (6000 blocks)
3. try fighting with your friend with arrows and some potions
4. You will notice sometimes entities such as arrows and potions tend to lag in mid air