Comparing fulfillment methods: Is cross-docking right for us?

We're hitting a ceiling with our standard pick-and-pack fulfillment model for our fastest-selling items. I'm researching different cross docking solutions to see if they could streamline our process, but I'm having trouble weighing them against just optimizing our current warehouse or using a standard 3PL. For businesses that made the switch, what specific problems did cross-docking solve that other methods didn't? I need to understand the practical difference in outcome.