Optimize your catalog regularly via File > Optimize Catalog to maintain speed, especially after heavy editing sessions.
Increase the Camera RAW Cache size in Preferences (at least 20GB-50GB recommended) to speed up image rendering. Adobe Lightroom Classic 2021
Replaced the older "Split Toning" with a more sophisticated three-way color wheels system, allowing for finer control over shadows, midtones, and highlights. Optimize your catalog regularly via File > Optimize