Open Sentinely if
- You want to know why your Mac is slow, not just which number is high
- You run AI coding tools, dev servers, or chat apps that leave helpers behind
- You want each fix reviewed first and measured afterwards
Sentinely
Sentinely and Activity Monitor
Activity Monitor is built into every Mac and shows memory in detail. Sentinely reads the same kind of numbers, says what they mean, fixes the cause after you review, and measures the result.
The short version: Activity Monitor is free, built in, and the right tool if you want the raw numbers and know what to do with them. Sentinely is for when you want to know why your Mac is slow, what to do about it, and whether the fix worked.
Activity Monitor's Memory tab shows a memory pressure graph, swap used, compressed memory, and how much memory each process uses. You can sort by memory and quit a process. It is a good place to start, and the guide How to find what's slowing down your Mac walks through it step by step.
Sentinely starts from the same kind of signals: the kernel's memory pressure level, swap, and each process's memory footprint. It groups processes by what started them, so dozens of helper processes become "AI-tool helpers left running after their app closed". It offers a fix you review, re-checks each process before acting, and writes a measured receipt afterwards. When nothing is wrong, it says so.
| Topic | Sentinely | Activity Monitor |
|---|---|---|
| Memory pressure and swap | Reads the kernel's pressure level, swap used, and how often memory is read back from swap. | Shows a memory pressure graph, Swap Used, and Compressed on the Memory tab. |
| Per-process memory | Groups processes by app or by what started them, with an estimate per group. Groups of shared processes are shown as "up to". | Lists each process with its memory. You can sort and search. |
| Explaining the cause | Says in plain language why something is holding memory, such as a closed editor's leftover helpers or a model still loaded. | Shows the numbers. Interpreting them is up to you. |
| Fixing it | Fixes you review first. Apps quit the normal way. Re-checks each process just before acting. Only your own processes. | Quit or Force Quit a selected process. |
| Proof afterwards | A receipt measured at ten seconds and one minute: memory freed, and pressure and swap before and after. | Live numbers. Comparing before and after is up to you. |
| Watching in the background | Menu bar monitor and alerts when pressure stays high or something keeps growing. | Its Dock icon can show a live graph. Check Apple's current guide for the options. |
| Price | The check, monitor, alerts, receipts, and first fix are free. See the app page for Pro. | Included with macOS. |
Activity Monitor details as of October 2026, from public pricing pages and reviews. Check the vendor's own pages for current plans and features.
Which one to open
Open Activity Monitor if
- You want every process and every column, live
- You already know which process to quit
- You are looking at CPU, energy, disk, or network rather than memory
Questions
Do I still need Activity Monitor?
It is built in, so you have it either way. It is the right tool for CPU, energy, disk, and network, and for looking at any process in detail. Sentinely is focused on memory.
Why do Sentinely's numbers differ from Activity Monitor's?
Sentinely groups processes and uses each process's memory footprint, including compressed memory. For groups of processes that share memory, its estimate is "up to", and the receipt shows what was actually measured afterwards.
Activity Monitor and macOS are trademarks of Apple Inc. This page describes Activity Monitor from Apple's published support documentation and does not claim to cover every feature.