MacWall's design goal is that you forget it is running. Video frames are decoded by Apple's media hardware through VideoToolbox and composited with Metal, so the CPU is not decoding pixels — and when nothing is visible, playback stops instead of running in the background.
Pause rules
- Pause on battery — stops playback whenever the Mac is unplugged. The single highest-impact setting on a laptop.
- Pause in full screen — a full screen app covers the wallpaper, so decoding it is pure waste.
- Pause on display sleep / lock — always on. Nothing decodes while the screen is off.
- Pause on high CPU — yields automatically during exports, compiles, and other heavy work, then resumes when load drops.
- Pause on Low Power Mode — follows the system energy preference you already set.
Verify it yourself
- Open Activity Monitor → CPU tab.
- Search for `MacWall` and watch the % CPU column with a wallpaper playing.
- Switch to the Energy tab and check Energy Impact over a few minutes.
- Pause from the menu bar and watch both values fall to effectively zero.
On a normal plugged-in desktop session, MacWall typically sits well under 1% CPU. Paused, it decodes nothing at all. The methodology and numbers are broken down in the performance guide.
If usage looks higher than expected
- Check the source video. A 60 fps 8K import costs far more to decode than a 4K 30 fps loop. Re-encode using the guidance in Import your own videos.
- Check codec support. Unusual codecs can fall back to software decode. H.264 and HEVC always use hardware.
- Count displays. Separate loops on several 4K panels multiply decode work; mirroring one loop decodes once.
- Check for a competing wallpaper app. Two apps fighting over the wallpaper layer will both keep working — and both keep drawing.