My project is over 20gb, and my editor is REALLY slow long ago. Any operations with AssetDatabase take 30-40 seconds, updating prefabs takes 30+ seconds, etc.
But the most annoying part saving a scene. Sometimes its instant, but sometimes it takes over a minute (same scene, no changes in both cases). Every time I save its a lottery. Below is a screenshot from profiler after saving a scene when it took over a minute: