Instancify Plugin For Cinema 4D
https://www.youtube.com/watch?v=Sbmr0SCgHFc
Instancify is a workflow plugin that finds all objects with identical topology, retains a single one as the Source Object and converts the rest to instances by connecting them to the Source. This way, if your scene has many identical objects, you can quickly convert them to instances. You can chose to convert a single object, selected objects or all objects in your scene.
The Plugin version is the folder called "instancify".
If you don't want to install the plugin, you can use the Script version, and it performs identically. Load the script in the Script Manager, and press "Execute".
This is a plugin from Athanasios Pozantzis (Noseman).
You can follow Athanasios on Twitter here: https://twitter.com/nosemangr
Or like and subscribe to his YouTube channel: https://www.youtube.com/channel/UCkWGnSaQR_XBMe3Yx4WHJ5Q