I am running a SMP server which has about 5-10 people on at a time. It is running Spigot. The problem is that there are way to many mobs spawning. In 'bukkit.yml' the mob cap is set at 70. In these screenshots there are hundreds of mobs spawning. It is causing the tps to be on average around 10. Using /kill @e[type=zombie,distance=..100] for each types of mob makes a huge difference, but within a hour the situation is just as bad. See this thread for images. https://bugs.mojang.com/browse/MC-196264