Question about server lag and VIEW_DISTANCE

[mario-hess]

The server runs on a Raspberry Pi 4. When players are far away of each other, it lags (very noticable when driving on rails).
I tried different values for MEMORY but it doesn't seem to do anything.
Is there a known solution to this?
Also I'd like to ask what the default value for VIEW_DISTANCE is, because it is empty in the docs.
Thank you very much!

[itzg]

Check to make sure your physical disk I/O isn't maxed out. I believe I/O can make a big difference with various chunks being loaded concurrently.

As for defaults, they will be the ones here

https://minecraft.wiki/w/Server.properties

So, view distance defaults to 10.