New iMac M4 Freezing up after 15.5 update

An M4 iMac client of mine called after he spent several hours on the phone with Apple trying to fix this about 2 months ago. Apple created a new user account but it didn't help.

About 6 weeks ago, I pounded on this problem with EtreCheck Pro in Sequoia 15.4. Just to review, in the middle of working the iMac would freeze and beachball for 5-15 seconds. This happened frequently during the day and made it nearly impossible for my client to work.

TRIED STUFF (6 weeks ago)

EtreCheck Pro’s reports guided me to a blanket approach: reindexed SpotLight, reset the lsd db, deleted ShortCut app because a related daemon crashed it, unplugged a very old USB hub, deleted TimeMachine localsnapshots, ran DiskUtility on all SSD partitions, deleted user library caches folder files, reset Bluetooth because its related daemon crashed, unchecked all Spotlight category settings because a related background process had high-ish cpu usage. 

I told the client to add a SpotLight category back one at a time only after a couple of days of no intermittent freezing.

One or more of the above fixed it temporarily.

PROBLEM RETURNED

The client said the problem slowly returned over the last 6 weeks to the point its hindering his work again.

I asked him what SpotLight items he added back (check boxes in SpotLight settings). He said he didn't add any back and left them all unchecked as I left them. That was a key piece of info.

I wondered what type of program other than Spotlight, which is completely unchecked, would gradually make the problem return? Maybe a memory leak in an app. I told him to update his Mac to 15.5.

The problem persisted.

SEEMING FIX (5 days ago)

So what feature gradually grows output as a feature besides cache files? 

TimeMachine localsnapshots, if you have TimeMachine enabled. This M4 iMac has a 2TB internal SSD that's half full, so TM has its way spewing localsnapshots over the remaining 1TB "free" space.

So I deleted localsnapshots again. ( Terminal: tmutil deletelocalsnapshots /    )

I kind of hate localsnapshots and wish Apple would let users turn them off while keeping TimeMachine running just on external drives. In hundreds of Macs I service, the only time a client needed a localsnapshot was after they lost their external drive but localsnapshots didn't go back far enough and were useless.

Plus, DiskUtility FirstAid often finds problems with one or more TM localsnapshots. It's much faster to delete them before running FirstAid. Plus localsnapshots are a privacy issue because they contain files you deleted probably without realizing that they’re still in localsnapshots until localsnapshots churn over.

But I digress.  

REPORT (yesterday)

Five days after I deleted localsnapshots on the M4 iMac, the client reported that the problem hasn’t returned. That's twice in 6 weeks that deleting localsnapshots stopped the problem.

But I expect it’ll gradually return as TM localsnapshots accumulate, so I’m going to show the client how to delete localsnapshots without my help.

My client wanted to disable TimeMachine in order to disable localsnapshots but I can’t risk him not having backups.

I just tested a macOS Shortcut app shortcut for deleting them: in the Shortcut app: settings / advanced - allow running scripts, then in the app not settings choose Terminal, then Run Shell Script, then replace “echo Hello World” with "tmutil deletelocalsnapshots / “ (without the quotes; you don’t need to press return and it doesn’t need sudo).

Right-clicking (or 2-finger tapping) the shortcut in the Shortcuts app lets you rename it and Add to Dock.

Just to review not in Shortcuts but just in Terminal:

List localsnapshots, type tmutil listlocalsnapshots / 

(then press return)

Delete them, tmutil deletelocalsnapshots /

(then press return)

In the Shortcuts app I only used the delete command.

I'm not thrilled about enabling "allow running scripts" because it lowers security, but I'm just doing it for this one client.

And I’ll also put the Terminal app on the iMac’s Dock and show my client how pressing the keyboard's up arrow shows the last command, likely tmutil deletelocalsnapshots / , so he can just press return to run it. If he's ok with that I may delete the shortcut and disable “allow running scripts.”

There is no problem using Migration Assistance - provided that you choose to migrate ONLY the user accounts. This makes it easy to transfer all the content and leave behind old applications, extensions and daemons.

I have been using this for nearly two decades and have all my content from way back, but none of the old software.

It is easy to make such a correction even after the fact, in today’s Macs.

1) Update your Time Machine backup

2) System Settings->General->Transfer or Reset->Erase All Content and Settings

This does not erase the drive or the OS

3) Migrate ONLY the user accounts from the backup made in step 1

4) Install any apps from App Store or developer websites

QUESTION 1 : did people with this thread's problem use Migration Assistant to set up their new Macs?

Almost all my clients use Migration Assistant from TimeMachine backups to set up new Macs.

Many clients owned multiple Macs starting around 2001, so Migration Assistant transferred ancient apps and system stuff from Mac to Mac to Mac over the last 24 or so years. E.g., their 1st Mac was in 2002, 2nd Mac in 2010, 3rd Mac in 2017, 4th Mac in 2025.

My client with the freezing problem did this.

His M4 iMac had numerous obsolete apps (slash-icon apps with very old file dates) and ancient internet plug-ins, plist files and other system gobbledygook as far back as 2003.

Before and after running EtreCheck Pro, I deeply cleaned his M4 iMac of ancient system and app files, e.g., plists, apps, preference panes, printer files, extensions, root and user library launch items and other hidden stuff. But no doubt I missed something.

Deleting TimeMachine localsnapshots temporarily solves the problem of intermittent freezing, but I wonder if using Migration Assistant from a series of old Macs brought over the culprit.

This might explain why it’s so hard for Apple and others to troubleshoot without completely erasing a Mac.

Completely erasing the M4 iMac and setting it up without Migration Assistant would probably confirm this. If it were my Mac, I'd do it, but the client can't spare the time or money for labor.

Apple can’t practically replicate Migration Assistant carryover from a series of very old Macs.

In 2024 I started recommending not using Migration Assistant every 3rd or 4th Mac.

Instead, manually drag-copy personal files from a TimeMachine backup drive and install apps from scratch. Then on the next new Mac, use Migration Assistant again.

Though Migration Assistant has checkboxes to include system settings and apps, clients just plow through the checked defaults. It's safer to not risk contamination with Migration Assistant every 3rd or 4th Mac.

QUESTION 2: did anyone with this problem set up their new Mac from scratch, i.e., without Migration Assistant?

Owl-53 is right about your free space. It's entirely not sufficient to promote efficient system and application performance. The write speed reflects that:

 Write speed: 126 MB/s

    Read speed: 1022 MB

For am M4 Mac it should be closer to

Write speed:3088 MB/s

Read speed:2444 MB/s

which is why my Mac Mini M4 is capable of.

You should get an external SSD drive and move large items, like your Photos Library, Music Library, etc. to it and run them from there.

If budget is a problem the following setup is a good solution:

I have several 1 TB units and they are an excellent choice for the money.

It's possible your new M3 Mac has a different issue. I'd first try unplugging all external storage because it's so easy. I've seen horrible Mac sluggishness caused by bad external drives that gave macOS fits, especially during mounting. I saw this again just a few weeks ago.

This thread's mainly about M4 Macs running Sequoia 15.5, but maybe the M3 Ultra has the same problem as the M4 line.

Call Apple Support. Even if they don't fix it, they'll log the problem and know more people are experiencing it.

It'd take a lot of your time, but if you've only had your new Mac less than 14 days, you can return it no questions asked then order a replacement. You don't need tech support authorization etc., just the receipt. Take it to a local apple store. They really don't ask why. You could hate its color. They don't care before 14 days.

I've used and serviced Macs (and Windows and Linux PCs) for decades and hadn't encountered this mysterious intermittent severe macOS pausing / almost-freezing until this year.

Activity Monitor is like Windows Task Manager: they both show CPU, disk and memory usage for what's currently running. This problem is extra tough to nail down because Activity Monitor doesn't directly reveal it, plus relatively few Macs have the problem plus it's intermittent even on Macs that have it.

Currently, this thread's "I also have this problem 'Me too'" number is 10. Tiny compared to 75% of Macs running 15.5 so far, according to Telemetry Deck https://telemetrydeck.com/survey/apple/macOS/versions/). In 2024 alone, Apple sold ~22.5 million Macs. The M4 line came out in late 2024. So this year's Mac sales are mostly M4 models. But at 75% adoption, macOS 15.5 might be running on 75 million Macs if 100 million Macs can run it (roughly 2018 Macs and later, so 7 years worth of Mac sales, probably more than 100 million).

Sequoia's overdue for a macOS update in my opinion. It has other mysterious issues (e.g., iCloud syncing). Apple's probably too busy with its next release, Tahoe (expected in Sept/Oct, in Beta 3 now).

Plus, Apple hasn't needed to fix a security vulnerability since May 12th.

Apple irregularly updates macOS, very roughly every 4-6 weeks. It's not scheduled like Windows "Patch Tuesday", 2nd Tuesday of each month).

Sequoia

None yet Jul 9 (57 days and counting but maturing needs fewer fixes except for security issues)

15.5.0 May 12 (26 days)

15.4.1 Apr 16 (16 days)

15.4.0 Mar 31 (20 days)

15.3.2 Mar 11 (29 days)

15.3.1 Feb 10 (14 days)

15.3.0 Jan 27 (47 days)

15.2.0 Dec 11 (22 days)

15.1.1 Nov 19 (22 days)

15.1.0 Oct 28 (24 days)

15.0.1 Oct 4

Additional Mac troubleshooting sources and tools:

• Mr. Macintosh: mrmacintosh.com (since you have a new Mac, ignore its OpenCore Legacy Patcher info, which only applies to very old "unsupported" Macs)

• The Electric Light Company Mac: eclecticlight.co ( that's dot "co")

• TidBits: tidbits.com

• Objective-see for Mac security: objective-see.org

PS My client with this issue just reported that deleting localsnapshots continues to remove the symptom (intermittent freezing).

To skip the Q&A session, just download the Application Etrecheck directly from the Developer. 

It’s a diagnostic tool that doesn’t change your computer at all. It gives you a clear and easy-to-read list of both your hardware and software. 

You can get it for free or pay for extra features. And don’t worry, the report won’t reveal any personal information. 

Once you’re done, just copy and paste the full report using the Additional Text Icon.

Lastly - should you decide to use and post the Report now or at a later time, we are willing to have a very close look and offer some insights 

I get that 256GB is a pretty small drive, but in this case the user is not at fault, IMO.

The "available space" is pretty large (over 160GB), so it's not like the user has filled up the drive; but alas, the free space is pretty small.

This is one case where the way macOS holds on to "purgeable" space is hurting the user badly. It is adding insult to injury that the purgeable space is over half the total space of the drive!

I'd try restarting in Safe Mode, log in, and then restart normally, but it can be hard to force macOS to release space, even when, as in this case, it is desperately needed.

The report indicates that the Time Machine snapshots make up for about one day, which is normal, so that is not what is holding on to all that space.

Just to add to what has been said, a 256GB SSD is very small for Sequoia and added software. You barely have 10% free space. Normally 20%+ is recommended. 25% to 33% is better for an SSD. You either have to delete some apps/data to free some space or, get a larger external SSD, say 1TB to run Sequoia from.

I like that idea, but I delete my localsnapshots in 4-5 seconds using this method:

• command-spacebar
• type "term" then press return (to open Terminal)
• use the up arrow to select previously used command, "tmutil deletelocalsnapshots / " then press return
• command-q to quit Terminal

Of course, the first time you have to type "tmutil deletelocalsnapshots / " without the quotes then press return so it'll appear with a future up arrow.

JNoel54 wrote:

<Report.log>

One and meant in a Friendly Way

To get the replies to your question in chronological order by Date 

Click on your User Name  >>   >> " Edit Profile and Preferences "

Scroll way down and look for >> >> " Other Preferences "

Change the >> >> " Default thread sort " to Oldest 

Two - Thank you for the report

A very fast review, though we will going into greater details later

" Low disk space - This computer is running critically low on free hard drive space. "

disk0 - APPLE SSD AP0256Z 251.00 GB (Solid State - TRIM: Yes)

Size: 245.11 GB

Free: 26.73 GB

Available: 199.23 GB

The less Empty Space the harder the computer will work to Find Empty Space

The harder the computer works the slower it will preform

Sadly, as you have earlier noticed, this is exactly what is occurring

OP wrote " The cursor won't move, then moves after a few moments. I type a few words in Pages, nothing appears, then several words come all at once. As I type here, the same thing happens. "

EDITED - self

Does your client shut down his M4 at night or just sleep it. If just sleeps it have them try to shut down each night. That will clear out temporary system and application cache and swap files each night. If your client hasn't shut down for over 5 days the first shunt down should be a Safe Mode boot followed by a normal boot.

That might be a good idea.

Does the migrated user account include the following in the user's Library folder?

- ancient abandoned / leftover hidden files (dot filename) in the home folder, ancient plists and folders in Preferences, old apps or aliases in Preference Panes, Application Support subfolders of abandoned products, old items in LaunchAgents, Internet Plug-ins (safari), Containers (introduced ~2011 in Lion 10.7), Group Containers.

I might try your approach someday if migrated user accounts don't include the above.

For now, I prefer to skip Migration Assistant every 3rd or 4th Mac and manually drag-copy personal files from the TimeMachine backup: Documents & Desktop (not necessary if iCloud syncs those), Downloads, maybe iCloud archives if present, loose pics in the Pictures folder (i.e, not the Photos library, itself, which will sync over iCloud), Music, Movies and any other user library user-created data folder in the Home folder.

The time it takes to manually drag-copy those from a TimeMachine backup drive is comparable to Migration Assistant doing it but ensures a very clean system.

PS Another new client used Migration Assistant over 3 Macs and the current old-ish Mac inherited an old Internet Plug-in (a folder actually) with a suspicious generic name running a java-applet that can't be deleted without rebooting with SIP off (no error but just no right-click "move to trash" option and no response with keyboard command-delete). That clients replacing that Mac with an M4 Mac mini but won't use Migration Assistant.

From what appears in the report

There are not Software issues per se that account for this issue

You may consider " Optimize storage space on your Mac " which is related to iCloud usages

The other aspect you might consider to Remove GarageBand and all the added Music File associated with this application

Hopefully this will get the computer some additional Empty Space

Though to be honest

Purchasing a new computer with the smallest 256 GB drive may have sounded a good idea and factor in the extra costs for a larger drive Capacity

One ( you ) may have been short-sighted in that 256 GB Drive capacity is and will remain a Challenge to maintain

I can only suggest in Disk Utility, Disk First Aid to show all devices, run Repair on all items in the left side, top down, then reinstall the OS.