Huge lags in "spread to show desktop" on extended display

OS version: macOS 15.6.1

Steps to reproduce:

1. Connect your Mac to an extended display (an iPad with sidecar is also fine)
2. Change your desktop wallpaper to Ventura
3. Leave only one window on desktop
4. Slowly spread your fingers on trackpad to show desktop

Notes:

1. You can also use sidecar on an iPad if you don't have an extra monitor
2. Wallpaper matters. The one that is easiest to reproduce is the Ventura wallpaper.
3. Make sure to spread your fingers on trackpad to show desktop, do not click desktop.
4. Compare the animations of showing desktop with one and two windows open. Two windows is significantly smoother than one window.
5. If you do not see lags, wait a few minutes after you change the wallpaper to Ventura.