We have had constant CPU lag over the last 24 hours and I am having trouble locating the reason. The first thing that I did was plugin testing and I also changed the settings of the 3D map to use fewer resources. I have for example changed how water it processed and how shadows are displayed. I also now switched off map updates on grass & tree growth and many more smaller events. The map might not be as nice and 100% accurate anymore but it helps reducing the lag.
Further I have installed now max mob limits per world and overall. This will cause some of your mobs to disappear. The overall goal should be that everyone keeps the amount of animals that they actually need for that specific moment. There should be no-one having to keep 25 wolves around, or 20 sheep in every color unless you are building something – in every color. Specially mobs that eat grass cause lag since the server has to calculate their movement, their eating AND the grass growing back which is causing lag.