I recently built a endermen farm and realized that the mob cap is a bit restricted. If I let the endermen spawn until it is full I get 22 endermen. Even though the mob cap is 70 the mobs are capped at 22 because the equation value * chunk_count / 256 or 269 (I don't know which). The chunk count is determined by the server render distance squared which I am guessing is 9 by the amount I have spawning. I don't think you should change the render distance but bumping the mob cap up a bit to compensate for the lower render distance would be nice as long as the server handles it well.
~ @Etherion
Is this /warp wild? If so, tough luck there my friend, the mob cap increase by the number of players in the current world.
If it's towny then good luck. I've suggested this time and time again up to no avail to the point I spawned in over 5000 mobs in a small area and didn't cause any issues at all. This was when we had over 40+ players online at once. Their favourite line would be "it would cause too much lag.
