Keep Mac Awake During Long Renders

Renders are CPU-bursty, not steady

Final Cut, DaVinci Resolve, Premiere, Blender, Xcode, ML training jobs — they all hit the CPU in bursts. A render reads files (light), processes (heavy), writes results (medium), waits for storage (light), repeats. The instantaneous CPU number can swing from 95% to 12% in a single second.

A simple "CPU above threshold" condition isn't enough. The first time CPU dips below 60% mid-render, the condition fails, the Mac sleeps mid-export, and you wake up to a half-finished file.

Sustained-CPU windows fix it

The sustained-CPU trigger checks an average over the last N seconds, not a single sample. If CPU has been above the threshold on average for the last 1 minute, the condition passes — even if there were dips along the way.

Four options:

• 10s — quick builds, short encodes
• 30s — typical photo exports, light renders
• 1m — Final Cut / Premiere exports, Blender previews
• 5m — full Blender renders, Xcode CI builds, ML training

Set it up

1. Open Settings (menu bar → Settings…).
2. Scroll to Only Shake If.
3. Turn on CPU is above threshold.
4. Set the threshold (60–75% is a good starting point for renders).
5. Pick a sustained window from the segmented control: 10s / 30s / 1m / 5m.

The full overnight-render recipe

Combine sustained-CPU with the rest of the engine for a robust overnight setup:

• CPU above 60% sustained for 1 minute
• Allow display to sleep (so the Mac stays awake but the screen turns off)
• Paused When: On battery (so it doesn't drain if you accidentally unplug)
• Auto-disable after 12 hours (safety net)
• Save as a "Render" Session for one-click switching

Hit start on the render, the Mac stays awake until CPU drops sustained below the threshold (i.e., the render is actually done). Then it sleeps. Then auto-disable kicks in.

Picking a threshold

The right threshold depends on what else is running.

• Dedicated render Mac: 50–60% threshold is plenty. Background system load alone is usually under 30%.
• Mac with Slack, Chrome, etc. open: bump to 70–75%. Idle-but-busy modern apps can sit at 30–40%.
• M-series Macs: same numbers, but renders often finish faster than the sustained window — set sustained to 30s rather than 1m to avoid the awkward "render done, Mac slept, finder beach-ball" race.

App-specific tips

• Final Cut Pro — 60% / 1m sustained. Pair with "Pause when on battery" because exports drain fast.
• DaVinci Resolve — 70% / 1m. GPU-heavy renders may not light up CPU fully; consider also matching "App is open: Resolve".
• Blender — 50% / 5m. Long sustained renders, low overhead per pass.
• Xcode — 60% / 30s. Builds are spiky; 30s window catches sustained build phases.
• Stable Diffusion / ML training — 40% / 5m. GPU-heavy; CPU stays modest but consistent.