What did the dominance of slave-morality do to the world in Nietzsche's estimation?

How did the advent of the dominance of the slave-morality change the world from what it had been under the master-morality. eg did it make it sick or change humans fundamentally? Quotes from the text would be appreciated (I am using on the genealogy of morality translation by maudemarie clark and alan j. swensen. I also have the portable Nietzsche by Kaufman)