In-camera motion blur is a time intensive and therefore costly effect that usually isn't worth it unless you're working on an expensive production. Re:VisionFX Reel Smart Motion Blur or RSMB is a great way to cut out the time of rendering in-camera motion blur so you can just do it in post. There are a few important things to know to get it working properly.
If you have a heavy, or long AE project, rendering is likely a gigantic bottleneck for you... there is a better way.