"You're moving slowly and dropping tasks. That is impacting the business and we are losing customers. This needs to change by next month/quarter/whatever."
vs.
"YOU ARE A DUMB DOLPHIN BLAH BLAH BLAH"
Massive difference.
The former is a warning rooted in a sincere desire to lead the org/employee towards positive change. The latter is verbal abuse that accomplishes nothing but placating the ego of the abuser.