--- title: "Why is my Mac slow, hot or crashing? — iSurge" description: "Why your Mac is slow, hot or crashing, how to check it yourself, and how iSurge warns you only when a problem lasts, naming the app behind it." url: https://isurgemac.com/blog/mac-alerts-slow-hot-crash/ --- [BLOG](https://isurgemac.com/blog/) # Why is my Mac slow, hot or crashing? iSurge stays quiet until something needs you, then names the app. Why your Mac is slow, hot or crashing, how to check it yourself, and how iSurge warns you only when a problem lasts, naming the app behind it. By Ruthran Baskar · 27 October 2026 · 6 min read IN SHORT - A slow Mac is almost always one of four things: an app holding the CPU, memory running short, a nearly full disk, or heat. - You can check each one by hand in Activity Monitor and in System Settings › General › Storage. - iSurge watches for all four, and for crashes and low batteries, and speaks up only when a problem lasts. It names the app behind it. - Missed an alert? Insights keeps the last 7 days of them, each with its button. Your Mac gets slow, the fan comes on, or an app just disappears. The cause is nearly always one of a few things, and macOS will tell you which one if you know where to look. Here is where to look by hand, and then how iSurge does the looking for you and stays quiet until something needs you. ## Why is my Mac slow? Four causes cover most cases: - **One app is holding the CPU.** A stuck browser tab, a build, an export or a sync that never finishes. - **Memory is running short.** When apps want more memory than the Mac has, macOS moves some of it to the disk. That is called swap, and the disk is much slower than memory. - **The disk is nearly full.** macOS needs free space for swap, caches and updates. With little left, everything waits. - **It’s hot.** When the chip gets too warm, macOS lowers its speed to cool it down. ## How to check it yourself - **CPU:** open Activity Monitor, pick the CPU tab and sort by % CPU. It counts one core at a time, so 200% means two full cores. [Why that number confuses people](https://isurgemac.com/blog/a-thousand-processes/). - **Memory:** in Activity Monitor’s Memory tab, look at the Memory Pressure graph at the bottom. Green is fine, yellow is tight, red is short. Swap Used shows how much is on the disk. - **Disk:** open System Settings › General › Storage. - **Crashes:** open the Console app and pick Crash Reports. macOS keeps them in `~/Library/Logs/DiagnosticReports`. This works, but only after you notice something is wrong, and by then you have been waiting. Activity Monitor also lists every process, so one browser can be dozens of rows. That is the gap iSurge fills. NOTIFICATIONS ## What does a memory pressure warning mean? Memory pressure is macOS’s own word for how hard it is working to find room. High pressure means it is squeezing memory and moving parts of it to the disk, and that is when a Mac starts to feel slow. iSurge says **Your Mac is low on memory**when macOS’s memory pressure stays high for 30 seconds. It names the app using the most and how much it holds, and offers Quit. If the Mac is still short an hour later, with a quarter of its memory on the disk, you get**Your Mac is still low on memory** once more. Then it stays quiet until the problem clears. You can also be told when one app holds more than a fifth of your Mac’s memory, at least 2 GB, for 2 minutes. That one is off until you turn it on, because a big app is not always a problem. NOTIFICATIONS ## How iSurge tells you iSurge lives in the menu bar and, on a Mac with a notch, at the notch. On a notch Mac an alert grows out of the notch. Without one, it is a normal Mac notification at the top right of the screen. Each one says what happened and which app, with a button: **Show**opens the page about it, and**Quit** lets you pick Quit or Force Quit. Alerts come out of the notch, each with its own buttons. These three are from the Dev tab. A new install starts with **Only important** in Settings › Notifications. That covers: - **CPU is at its limit:** the whole Mac above 90% for 5 minutes, with the app behind it and how many cores it is using. - **Your Mac is low on memory**, as above. - **Your disk is almost full:**under 10% free. If Disk has looked, it also says how much could be cleared, with a**Review** button. - **Your Mac is running hot:** the CPU above 95 °C for 2 minutes, naming the busiest app. - **Low batteries:** your Mac’s at 20% and 10%, and AirPods or another Bluetooth device at 20% and 10%. - **An app that quit unexpectedly**, and going offline. **About everything**adds the rest, such as an app above 80% CPU for 5 minutes, heavy disk writes, an app heavy on battery, a busy GPU, macOS slowing down to cool, and a restart suggested when the Mac has been on for 14 days and is short on memory.**Never** turns them all off. You can also open each group and switch single alerts. NOTIFICATIONS ## Why not an alert for every spike? A spike is not a problem. Every alert waits for its problem to last, and a short dip does not start the clock again. Once an alert is shown, it stays quiet until the problem has been gone for 10 minutes, and the same alert does not come back within an hour. A Mac that runs hot all afternoon tells you once. NOTIFICATIONS ## An app keeps crashing on your Mac: what now? When an app quits unexpectedly, macOS writes a crash report. iSurge looks for new ones every 30 seconds and says **Safari quit unexpectedly**, or whichever app it was, with two buttons.**Show**opens macOS’s report of the crash, and**Reopen** opens the app again. It only tells you about apps you open yourself. The background parts of macOS that crash and restart on their own are left out, and you hear about the same app at most once an hour. If one app keeps crashing, update it first. If that does not help, send the report to whoever makes it: it shows them where the app failed. NOTIFICATIONS ## Warnings that name the apps behind them Notifications are for when you are busy elsewhere. When you open the menu bar dropdown or the iSurge window, it also shows what is straining the Mac right now, one line each, up to three in the dropdown. In the window, Overview starts with **Your Mac is under strain** and a row for each. - **Memory is running low:** pressure high for 2 minutes, or at once when it turns critical. - **CPU is at its limit**or**GPU is at its limit:** 90% or more for 2 minutes. - **Mac is running hot:** 90 °C for 2 minutes, or at once when macOS slows the Mac down to cool it. - **Disk is almost full:** less than 10% free, with how much is left. - **Google Chrome is using 8.4 GB**, or whichever app holds over a fifth of the memory, and an app**keeping a core busy** for 10 minutes. - On battery: **Battery is draining fast**, and**An unused app is draining the battery**. Each line says how long it has lasted, or what is left, and knows the apps behind it. Click it and the page opens with those apps picked out. The ✕ hides a line for an hour; after that it comes back only if the Mac is still under strain. These lines show even with notifications set to Never, and in Compact mode the iSurge icon in the menu bar can turn orange too (Settings › Menu Bar). NOTIFICATIONS ## Quiet hours Turn on **Quiet hours** in Settings › Notifications and alerts are held back from 22:00 to 08:00. They are not lost: each one still goes into Recent alerts, so you can look in the morning. Your own Focus Timer still tells you when its time is up. WINDOW ## Missed one? Recent alerts in Insights An alert at the notch closes after a few seconds, so it is easy to miss. The Insights page in the iSurge window starts with **Recent alerts**: everything iSurge said in the last 7 days, newest first, four at a time with**Show all** for the rest. Each one keeps its button. A crash has Show and Reopen, a full disk has Review, and the rest have Show. They are kept in one small file on your Mac and never sent anywhere. Deleting your history in Settings clears them too. An alert from iSurge’s first version, and the kinds it had then. Since 0.4 the memory alert says how much the app holds, and CPU is at its limit is new. ## Questions ### Can I turn the notifications off but keep the warnings? Yes. Set Notify me to Never in Settings › Notifications. The strain lines in the dropdown and the window still show. ### Why didn’t a notification show up? Check whether Quiet hours is on, then press Send Test Notification in Settings › Notifications. If it says it was sent and you still see nothing, a Focus mode on your Mac may be hiding it. ### Does iSurge send my alerts anywhere? No. Recent alerts are kept on your Mac for 7 days and never leave it. iSurge runs on Apple silicon Macs with macOS 15 or later. It is $14.99 once, or $9.99 for a year, and it stays free for everyone who had it before 0.4. [See the prices](https://isurgemac.com/pricing/), or read [why it lives at the notch](https://isurgemac.com/blog/look-up/). ## Get iSurge Pay once, yours for good. [Buy iSurge](https://isurgemac.com/pricing/) Already have it? [Download](https://isurgemac.com/download) Requires a Mac with Apple silicon (M1 or later) and macOS 15 Sequoia or later. Notch features need a MacBook with a notch; everything else works on any supported Mac.