The new Vegas Pro 15 PIP (picture in picture) and SmartZoom FX are easy to use, but the render time is very slow compared to using the pan/crop tool.

A render of 8 second HD1080 clip just zooming one track (not actual pip with 2 tracks) with the new Magix AVC 30fps NVENC CODEC:

Pan/crop tool: 7 seconds (0.875x)
SmartZoom: 15 seconds (1.875x)
PIP: 32 seconds (4.000x)

This is with Nvidia 750ti and AMD 8350 Windows 10.