Knowledge Base

Mac performance guides

Honest command-line answers to what your Mac is doing, each checked on a real Mac, and where GaugeMon makes it easier.

kernel_task using high CPU on Mac

kernel_task using lots of CPU is usually macOS cooling your Mac: it takes CPU time away from other processes so the chip produces less heat. You cannot and should not kill it; reduce the heat and the load that cause it.

WindowServer high CPU on Mac

WindowServer draws every window on every display. High CPU comes from many or high-resolution displays, high refresh rates, transparency effects and apps that redraw constantly. Find the app with top, then reduce displays, transparency or redraws.

Check CPU temperature on a Mac (without sudo)

Without sudo, macOS has no built-in command that prints CPU temperature. pmset -g therm shows thermal warnings; on Apple Silicon even sudo powermetrics shows only a thermal pressure level. Degrees need an app that reads the temperature sensors.

Mac memory pressure yellow/red: what it means

Memory pressure is how hard macOS is working to find memory: green is fine, yellow means it is compressing and swapping heavily, red means it needs more memory than you have. Free memory near zero is normal; check memory_pressure and swap instead.

htop on Mac shows 0% CPU for some processes

macOS only lets a process read CPU and memory counters for processes owned by the same user, so htop without sudo shows 0% for root and system processes like WindowServer. Run sudo htop, or use top or ps, which are installed setuid root.

Check GPU usage on a Mac

Open Activity Monitor and choose Window > GPU History, or read the GPU's Device Utilization % from the terminal with ioreg -rc IOAccelerator. sudo powermetrics --samplers gpu_power adds GPU frequency and power.

Find what is draining your MacBook battery

Run pmset -g batt for the charge and time remaining, top -o power to rank processes by energy use, and pmset -g assertions to see what is keeping the Mac awake. Quit or fix the top offenders.

Check fan speed on a Mac

macOS has no built-in way to show fan speed on Apple Silicon Macs. On Intel Macs, sudo powermetrics --samplers smc reports fan speed. Otherwise you need an app that reads the SMC, such as GaugeMon.