Performance
Choosing a system monitor for Mac
Updated · Applies to macOS 14 Sonoma through macOS 27 Golden Gate
Start with Activity Monitor, which is free and detailed. Add a menu bar monitor if you want live numbers at a glance: iStat Menus for the most sensors and customisation, Stats if you want free and open source, or Softset Pulse for app-level totals, plain-language explanations, and developer tools.
We make Softset Pulse, which is still in development, so weigh our view accordingly. Checked 25 September 2026.
What’s worth watching
- CPU: sustained high use, not brief spikes.
- Memory pressure and swap, rather than “memory used”. See why.
- Energy: which apps drain the battery.
- Disk space: a nearly full disk slows everything.
- Network: when something is uploading that shouldn’t be.
- Heat: macOS slows the Mac down when it’s too hot.
The options
Activity Monitor (built in)
Free and thorough: CPU, memory, energy, disk, and network per process, with process sampling and open files. Its weaknesses are presentation: helpers listed separately, little history, and no explanations. See Softset Pulse vs Activity Monitor.
iStat Menus
The most detailed menu bar monitor: sensors, fan control, per-core CPU, weather, clocks, and deep customisation, as a one-time purchase (bjango.com). See Softset Pulse vs iStat Menus.
Stats
A free, open-source menu bar monitor covering CPU, GPU, memory, disk, network, battery, and sensors (github.com/exelban/stats).
Softset Pulse
Ours, in development. Groups every helper under its app, keeps history, explains in plain words what’s slowing the Mac, and finds open ports, dev servers, and idle processes with their project folders. It sticks to public macOS interfaces, so it shows thermal pressure rather than individual CPU temperatures or fan speeds.
For developers
Most monitors stop at processes. If you run local servers, look for port and project awareness, or use the Terminal commands in finding the process using a port.
Summary
- Occasional checks: Activity Monitor.
- Every sensor, always visible: iStat Menus.
- Free and open source: Stats.
- Answers, app totals, and dev servers: Softset Pulse (early access).