Animation Inspector is suddenly Unbearably Laggy

All models with animations have become horribly laggy in the Inspector. None of the character files are more than 20mb big. They were working fine a few days ago and haven't been modified in a few weeks and have worked smoothly for many Unity updates now. With the player character ones, scrolling takes extremely long (about 3-6 second delay). Typing an animation name takes about 3-6 seconds per letter to be typed! Hitting the play button previews the animation in about 1-2 FPS. I haven't installed any programs recently or updated Unity. I cleared the project's cache. Animations display perfectly in game and in the Animator when previewing and modifying transitions. This bug is pretty bad as it makes those menus painfully slow. I tried restarting my computer and making sure nothing else is open. Reinstalling doesn't fix it either. Character files that are low poly and have less animations are less laggy. It's very confusing. Things were very smooth for a long time and just became unbearably bad yesterday.