indeed, their split attack time has been increased by 2. This means goblins must attack 2 more time before they split into new goblins.
Why? With no auras, a smart person can easily have 15 goblins going. With a speed set, if there are enough creeps, you can get 30 goblins in about 15 seconds. This is too strong, being able to do nothing and outlevel everyone.