Steps to Reproduce:
1. Set BDS render distance to any amount, or be aware that Realm render distance is 10 chunks
2. Join the world with a client render distance higher than that of the host server (Higher than 10 on Realms, or higher than what was set in BDS)
3. Observe noticeable ingame lag, and major lag on host CPU/server resources

Observed Results:
Server lag/server resource use drastically increases as more players join with a client render distance higher than the host. Server lag/server resource use drastically decreases when players lower their render distances to match, or below that of the host.
Following REALMS-2980: This can also be tested through in-game means by setting a repeating command block to add a value to a scoreboard each tick. It will be noticeably slower than 20 ticks per second when the server is lagging.

Expected Results:
Server lag/server resource use are not affected by client-side render distance.