Open and Save dialogs are very, very, very slow

I'm at my wit's end. Open and Save operations using the File dropdown menu are insanely slow on my M1 Max MacBook Pro. This goes for the "Duplicate" button as well. Opening and saving files in all other ways (e.g. command-S to save, double-clicking a file icon to open, etc.) are just as fast as they ever were. I go out of my way to use these alternatives, but sometimes (e.g. when I want to "save as" there is no other easy option, and I just need to wait and wait and wait while the Finder does... what? This started on Sonoma, and I hoped that updating to Sequoia would help, but it didn't. The computer works perfectly in every other way. What could possibly be going on?