Option to disable passive mob-spawning around AFK players?

[nuttapillar]

I allow afk players on my server, and I'm fine with them running mob farms. But I could still improve performance if the game doesn't try to spawn pointless animals around them like cows, sheep, pigs, chickens etc. They should be treated as non-existent in that regard. Perhaps we could choose which mobs are enable/disabled around AFK players.