Right now there is 1 mob that spawn per second, in 12Kx12K map (more if this include both nether and aether, too), and that is way too little. We didn't have too much lag with 20 mobs/second, so we could increase it by 1 or 2. That would be much better, because when I go hunt cows/sheep's etc I need about 5 min to find 3 cows/sheep's, and I use sometimes use shift potions. Imagine how hard it can be for new users to find food when they are starting, then can get max 22 pork/ normal day, if they don't buy any, and average users eat 10 pork/hour. Only bad think I see in this is more people would use mob traps/exp grinders again.
HOSTILE mob spawn is 1 every second. (was 20 times a second) PASSIVE mob spawn is 1 every 16 seconds. (never changed) if you want passive mobs spawned then you have to spawn them yourself with /spawnmob
