How much CPU does MacWall use?

Where the decoding happens

MacWall plays wallpapers through Apple's video frameworks, which decode H.264 and HEVC on the Mac's media hardware instead of on the CPU. When nothing can see the wallpaper, behind a full-screen app or with the displays asleep, it stops decoding instead of playing in the background.

Playback mode makes a difference

• •System Wallpaper (macOS 26+): macOS plays the wallpaper, so MacWall can stay closed. The MacWall process uses 0% CPU after you quit; macOS still decodes the video.
• •MacWall App: MacWall plays the video itself and stays open while it does.

Switch between them in Settings → Wallpaper → Playback.

What raises the load

• •Your own videos: an 8K or 60 fps file takes far more decoding than a 4K loop at 30 fps.
• •The codec: ProRes, AV1 or VP9 inside your own video is converted when you set it, which takes a while. H.264 and HEVC play as they are.
• •Displays: each display with its own wallpaper adds decoding work. With System Wallpaper playback, displays showing the same wallpaper share one player.

For games, exports and builds in a window, turn on Pause when your Mac is busy in Settings → Battery & Performance.

Measure it in Activity Monitor

1. Open Activity Monitor and choose the CPU tab.
2. Search for MacWall and watch % CPU with a wallpaper playing.
3. Switch to Energy and watch Energy Impact for a few minutes.
4. Pause from the MacWall menu bar icon and compare.

With System Wallpaper playback macOS decodes the video in its own wallpaper process, so compare the whole Mac's CPU, not just MacWall's row.