Peer review is in crisis, but should be fixed, not abolished

Traditionally, scientific studies are published in peer-reviewed journals, which require other scientists to evaluate submitted research to determine its soundness for publication. Peer review is supposed to be acting as a stopgap for science that is not sound ; but it has become the slowest step in the process of sharing studies. Rather than simply bypassing peer review and contributing to increase an overloaded system, how could peer review be enhanced ?