The Performance Throttle
In an effort to maximize battery life on aging MacBooks, macOS includes a feature called “Low Power Mode.” When activated, this mode aggressively scales back the CPU clock speed, lowers the screen brightness, pauses background iCloud syncing, and reduces the display refresh rate. While useful in emergency situations where you need your laptop to survive a long flight, some users accidentally enable it permanently, or macOS may prompt you to enable it too aggressively. The result is a sluggish, unresponsive computer that struggles to perform basic rendering tasks, leaving you wondering why your expensive machine suddenly feels five years old.
Restoring Full System Power
To guarantee that your MacBook is always utilizing its maximum hardware capabilities and to prevent macOS from silently throttling your processor to save a few percentage points of battery life, you must completely disable Low Power Mode.
Click the Apple logo in the extreme top-left corner of your screen and select System Settings. Scroll down the left-hand navigation pane and click on Battery. In the main right-hand panel, look near the top for the Low Power Mode setting. To the right of this text, you will see a dropdown menu. It may currently be set to “Always,” “Only on Battery,” or “Only on Power Adapter.” Click this dropdown menu and select Never. The system will immediately remove the artificial performance limits. Your processor will return to its standard clock speeds, your screen brightness will unlock, and background processes will resume normal operation.