How to check how hard your Mac is working: CPU, memory and disk at a glance

27 October 2026 · 7 min read

To check how hard your Mac is working, look at five things: how busy the processor is, how much pressure the memory is under, how much the disk is reading and writing, how much data is moving over the network, and how busy the graphics chip is. One number is rarely the answer on its own. A processor at 90 percent for a minute while an export finishes is normal, and a processor at 90 percent for an hour while you read email is not.

Below: what each of the five numbers means, why memory pressure matters more than memory used, how to get a live graph, and how to keep a readout in the menu bar so you do not have to go looking.

The five numbers that matter

Processor (CPU). This is the share of the processor’s capacity being used right now. It jumps around, which is normal. What matters is whether it stays high when you are not asking the Mac to do anything. top in Terminal counts each core as 100 percent, so one busy app can read above 100 percent there, which is not an error. Foreman shows each app’s CPU as a share of the whole Mac, with the Mac’s total above the column.

Memory. Your Mac uses almost all of its memory almost all of the time, on purpose, because memory that sits empty is wasted. A full memory bar is not a problem by itself. The useful number is memory pressure, covered in the next section.

Disk. How much data is being read from and written to the drive. Heavy disk use is expected when you copy files, import photos or install an update. It is a clue when it never settles down, because something is working through a lot of files in the background. If that is your case, how to find what is writing to your Mac’s disk goes through it.

Network. Data sent and received. A fast, steady upload or download that you did not start is worth a look, because a backup, a cloud sync or an update may be running.

Graphics (GPU). The graphics chip draws everything on screen and also does video work and games. A high figure while you edit video or play a game is the job being done. A high figure with only a text document open is not.

Read them together. High processor and high disk together usually point to one busy program working through files. High processor with a quiet disk and network usually points to a program calculating something, or stuck in a loop. A quiet processor, disk and network while the Mac still feels slow often points to memory pressure, which is the number people misread.

Memory pressure matters more than memory used

Memory used will always look high on a Mac that has been on for a few days. macOS keeps recently used data in memory so apps open faster, and it hands that memory back when something else needs it. So a chart that says most of your memory is used does not mean you are short of memory.

Memory pressure asks a better question: is the Mac having to work to find room? When pressure is low, there is plenty of space and nothing is struggling. When pressure rises, macOS starts squeezing data to fit and, if that is not enough, moves some of it out to the disk, which is slower. When pressure stays high for long periods, apps feel sluggish and the beach ball appears more often.

A simple way to use this: if memory used is high but pressure is low, do nothing. If pressure is high and stays high while you work normally, you are asking for more than the Mac has, and the fix is to close what you do not need or, in the long run, to get more memory. The post on memory pressure and when you actually need more RAM explains the difference in more depth.

Where to read these numbers

macOS shows pieces of this without any extra software.

System Settings. General, then Storage, shows how much of the drive is full. That is a different question from how hard the disk is working, but a nearly full drive does slow a Mac down, so look there first if the Mac has felt sluggish for weeks.
The battery menu. On a laptop, click the battery icon in the menu bar. Under “Using Significant Energy” it names any app drawing a lot of power right now, which is a fair pointer to what is keeping the Mac busy. It shows names, not figures.
Terminal. The top command prints a live table of processes with the processor and memory each one uses, and the figures at the top cover the whole Mac. Press q to leave it. It is exact, but it is a wall of text, and the names it shows are the technical ones.

For a live graph of everything at once, with names a person can read, you need an app.

A live graph with Foreman

Foreman is a Task Manager for macOS, built the way Task Manager works on Windows. Its Performance page lists CPU, Memory, Disk, Wi-Fi and GPU down the left, each with a small graph beside it. Pick one and you get a large live graph with a minute of history, and under it the apps using the most of that resource.

Each page has more than the headline figure:

CPU can be shown as Overall or Each Core. It also shows user and system time, how many processes and threads are running, how long the Mac has been up, and how many performance and efficiency cores it has.
Memory shows memory pressure, which is the number to watch.
Disk shows read and write separately.
Wi-Fi shows data sent and received.
GPU shows the graphics chip’s load.

The point of putting them together is the comparison. If the processor graph is high and the disk graph is quiet, you know the busy thing is calculating, not reading files. You then pick CPU, see which app is using the most, and decide whether to end it or let it finish.

On the Processes page, the same five numbers are columns (Name, CPU, Memory, Disk, Network, GPU, Power usage), and above each column is the whole Mac’s total. Click a column header to sort by it, and the app doing the most is at the top. Apps are grouped with their helper processes, added up, so a browser shows as one row instead of a long list of helpers. Plain-English names are used for around 120 macOS processes, with the real name in grey beside them.

How to see which app is using the most CPU on a Mac covers that step by step.

Keep a readout where you can see it

The worst moment to go looking is when the Mac is already struggling. A readout in the menu bar is there before you need it, and a glance takes no effort.

Foreman puts a live readout in the menu bar. Its styles are “CPU graph and percentage”, “CPU and memory” and “Icon only”, and you pick one in Settings. Click the readout for a panel with CPU, Memory, Disk, Network and GPU, each with a live graph, and a “Using the most” list you can switch between CPU and Memory. Each entry there has an End Task button. Control-Shift-Escape opens the full window from any app.

Settings also has a refresh speed: “Twice a Second”, “Every Second”, “Every 4 Seconds” or “Paused”. Slower is fine for a readout you only glance at.

What Foreman does not do: it does not show temperatures or fan speeds, and it does not keep a history of what a process used after the app quits. App History shows what each app has used since it opened, and those totals reset when the app quits. Foreman costs $12 once for up to 3 Macs, and it is free for 24 hours, which is long enough to see whether the numbers answer your question.

What to do with what you see

Processor high, one app on top. Give it a minute if it is doing a job you asked for. If it is not, quit it normally first, and force quit only if it will not close.
Memory pressure high and staying high. Quit apps you are not using. Browsers with many tabs are the usual cause.
Disk busy with nothing running. Wait, because Spotlight, Photos or a backup is probably catching up, then look again in an hour.
Everything low and the Mac still feels slow. Check that the drive is not nearly full, and look at the startup items that open at login.
Everything high at once. Start with whichever app is at the top of the list and work down.

If you are working through a slow Mac from the top, why is my Mac so slow and how to find the app to blame is the place to start.