Here are the GPU Raytracing, Importance Map, and Cluster improvements found in 2023.4.
GPU Raytracing Enhancements - For users with Ada Generation GPUs, we improved performance.
Important Maps Quality - For adjusting the resolution of the importance map to the environment Raytracing properties, we added an Importance Map Quality option. Select the environment in the Material Editor and open the Raytracing section to find it. The following Python scripts were also added, as a result: getImportanceMapQuality() and setInteractiveIblSamplingQuality(value).