It had to be slower because hunter-gatherer technology takes a lot more real estate to support a few people than does agriculture. It basically won't support cities at all.
Only a creationist would make an argument like yours. Most people have more pride.
If it won't support them then the pressure is on to start agriculture.
What? People are going to stop having babies? I don't think so. They might start wars over resources and that might keep the population down. But then that sounds kind of familiar....
Genesis 6:13 - And God said unto Noah, The end of all flesh is come before me; for the earth is filled with violence through them; and, behold, I will destroy them with the earth.
Only an evolutionist would expect people to believe human population stagnated in a hunter/gatherer mode for almost 300,000 years. And left no evidence of civilization at all.