This function is not seen in C4D 2023.1 oc 2022.1.
(Added real-time mode (lightning bolt button on render viewport). In this mode, if possible, the film buffer is never moved between the host and the device. This means that compositing has to be done on the GPU, and it also enables a "real-time" display, which will display rendered images faster. These features require more VRAM to be available. It does not have a large effect on MacOS because Apple GPUs have Unified Memory.)