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How to find what's slowing down your Mac
Most slow Macs are short on memory, not old. This guide shows how to check memory pressure and swap in Activity Monitor, what usually holds memory, and where Sentinely helps.
Beachballs, laggy app switches, and a fan that will not settle usually have an ordinary cause. On a modern Mac, the most common one is memory: the apps you have open want more than the Mac has, so macOS compresses memory and then writes some of it to disk. Switching back to an app means waiting for its memory to come back.
You can check this yourself with Activity Monitor, which is built into macOS. This guide walks through it, then covers the usual culprits and where Sentinely can do the diagnosis, the fix, and the measurement for you.
Check memory pressure in Activity Monitor
Open Activity Monitor from Applications > Utilities, or search for it with Spotlight. Click the Memory tab. At the bottom is the Memory Pressure graph. Green means memory is available. Yellow means macOS is working to make room, for example by compressing memory. Red means memory has run out and macOS is using the startup disk as memory.
Next to the graph, look at Swap Used and Compressed. Then sort the process list by the Memory column to see which apps hold the most. A high Memory Used number on its own is not a problem. macOS uses spare memory as cache on purpose. Pressure is the signal that matters.
What usually holds the memory
The culprits are ordinary. Chat and work apps such as Slack, Microsoft Teams, Discord, and Notion can grow when they stay open for days. AI coding tools start MCP servers for every session, and some keep running after the tool closes. Dev servers outlive the terminal that started them. Language servers in VS Code and Cursor grow over long sessions. Ollama keeps models loaded for a while after each request, and Docker Desktop runs a virtual machine. Adobe Creative Cloud can keep helpers running when no Adobe app is open.
Activity Monitor shows these as individual processes, often dozens of them with similar names. Grouping them by what started them is the hard part.
When it is not memory
If the Memory Pressure graph stays green, look elsewhere. On the CPU tab, sort by % CPU to find a single process stuck at full load. A Mac that is very hot can slow itself down to cool off. A startup disk that is nearly full slows everything, including swap, and that is a disk job rather than a memory job. Disk Housekeeper previews what it would clear and sends removals to the Trash by default.
Where Sentinely helps
Sentinely does the same check in a few seconds and says what it means. It groups processes by what started them, names the cause in plain language, and offers a fix you review before it runs. Apps are asked to quit the normal way, and only your own processes are touched. After the fix, it measures at ten seconds and again at one minute, and writes a receipt: memory freed, and memory pressure and swap before and after. If nothing improved, the receipt says so.
The check, the menu bar monitor, alerts, receipts, and the first fix are free. If your Mac is fine, Sentinely tells you that instead of inventing a problem.
Should you restart?
A restart clears memory, but it also closes everything, and the same apps fill memory again once you reopen them. It is worth it when memory pressure stays high after you have dealt with what you can, and swap is very large. Sentinely only suggests a restart in that situation, never because of how long the Mac has been on.
Comparing tools
Activity Monitor and menu bar monitors such as iStat Menus come up in the same search. Our comparison pages say what Sentinely does and what to check about the other tool.
Questions
Do I need more RAM?
Maybe, but check first. If memory pressure drops once leftover helpers and long-running apps are dealt with, the Mac had enough for what you actually use. If it stays high with only the apps you need open, more memory would help.
Is swap bad for my SSD?
Swap writes to the startup disk, and SSDs handle a limited amount of writing over their life. Normal swap is expected on a Mac. What you feel day to day is the pause while memory is read back, which is why Sentinely measures the swap-in rate.