Command Block Lag

World lag. You can go into the world but can't do anything. It happened by placing a repeating command block and putting the 'Always Active' mode on. Then type in the command ' /summon irongolem ~ ~ ~' . When I did that it started spawning lots and lots of iron golems. After about 1.2 seconds the world was really laggy. The summary of the problem is: World lag mob overflow repeating command loop.