Mac Mini M1 Sluggish - Why?

Anyone want to take a stab at why my Mac Mini M1 (16GB / 1 TB) is sluggish.





Apps that are open

  • Safari
  • Photos
  • Messages
  • Omnifocus
  • WhatsApp
  • Fantastical
  • DevonThink
  • 1Password
  • Day One
  • Signal
  • Telegram
  • Drafts
  • Synology Drive Client
  • Backblaze
  • Time Machine
  • Carbon Copy
  • Elgato
  • Hazel

What am I currently doing mainly?

I have Photos and Day One open side by side adding more entries, but the whole system is sluggish.

Sound odd?

Definitely that memory pressure is a clue. It shouldn’t be consistently that high with that list of apps. What does your memory tab say as far as heaviest apps?

Agreed, it definitely looks like you’re out of memory. It could be too many apps running at the same time, try closing some down. It all depends what the apps are doing, e.g. are they performing backups or indexing. Also, Electron apps use a lot of RAM, are the messaging apps Electron (e.g. WhatsApp, Signal)?

When I was testing an 8GB M1 (which I returned as it was only temporary while I waited for a 16GB), closing apps caused the system to become more responsive relatively quickly. I found the 8GB was filled with 3-4 apps running, and then the system was noticeably slower.

The slowdown will be due to the system using the SDD as a cache.

Right; 1/3 the virtual storage being on disk is not a good thing.

Also, and this is hard to quantify, looks like significant network traffic all the time.

The two might be related. I would suspect a browser tab doing continual network I/O - but I wouldn’t want to home in on that just yet.

(As a performance guy, albeit on a platform with better instrumentation, I would do the “problem decomposition” thing of looking at where the memory is going using the Memory tab.)

If you look at the performance monitor, is there a safari tab near the top for CPU or Memory usage?

If I had to guess I’d say look at safari.
In my experience any time I have a huge memory leak like this it’s usually a safari tab stuck in a loop


The problem with diagnosing a memory leak is you have to see a ramp up in usage. We don’t see that - which doesn’t mean it DIDN’T happen.

(Yes, I have seen that on “big boy tin”.) :slight_smile:

What we have here is the “steady state aftermath”. And, ironically, anything in swap space is probably a victim.

JUST excellent debugging info from TS here. All information presented in a clear way.

Yeah, the memory is way too high for what the app list is showing.

What is happening in the background at this time? Are you heavily indexing stuff in DevonThink?

I have to agree on previous speculation of Safari and ram. Safari is a pig at the moment, and is telling me webpages are using significant memory, and I should close them. This is a bit of role reversal, that’s what macOS and Safari are supposed to handle.
I should probably just go back to Brave.

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You have a lot of data going out which would make me think BackBlaze has a lot to backup. How is it configured? I would start by closing one app at a time and checking memory usage to see who frees it up.

The heaviest task under memory is called “kernel_task” coming in at 12.65

@JKoopmans @JohnAtl

Agree that Safari is a pig, many sites that I go to, begin telling me webpages are using significant memory as well. I tried to go back to a “safari-only” lifestyle and avoid Chrome. But I may go back to Chrome, or maybe try something new. Unfortunately, the search results between browsers (Safari vs DuckDuckGo) are so very different.


I have the default settings for BlackBlaze (schedule is the recommended continuously)

These numbers are after closing out the following apps.

1 Password

Has Backblaze finished it’s initial backup of this machine? Have you changed anything recently that would give it a bunch of data to chew through?

I believe so, it has a scheduled 143 GB to do today. Same setup as I had prior to the Mac Mini purchase.

I have 2 passports drives connected at all times. (1 for TM, and 1 for CCC)
Backblaze does the scheduled back of the Mac Mini + TM (not the CCC)

The top 5 processes in Memory

Kernel_Task (12.5 GB)
Day One (3.95 GB)
VTDecoderXPCService (2.05 GB)
WindowServer (1.05 GB)
bztransmit (this fluctuates from the lowest I saw was 300MB to the highest of 2GB)

I would try to isolate which app being open causes that high kernel_task usage. That’s crazy high. You could also restart, then keep the same apps open to see if it returns.

I don’t know any methods to easily trace what kernel_task is actually doing and for which apps; others might.

Did you happen to turn on FileVault? I wonder if the drive is being encrypted.

As @ChrisUpchurch pointed out, T2 equipped Macs are always encrypted. ref

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It sounds like you have some sort of memory leak somewhere, but I think BackBlaze might be contributing to the sluggishness. Although I have always heard it shouldn’t do this, but with the default settings with a large backup to do, Backblaze slows down anything web based considerably. I don’t notice it once that backup is done though. I would pause the backup, and turn it back on when you are done for the day. See if that helps.

That is always my first step if things are acting weird and closing apps doesn’t fix it.

My understanding is that M1 and T2 equipped Macs the data on the internal SSDis always encrypted, regardless of if you have File Vault turned on or not. All turning on file vault does is protect the disk’s encryption key with your password.


That’s my understanding also. I did a clean install of Big Sur on my 2018 Mac mini and FileVault was not turned on when it completed. When I did turn it on it was instantaneous- i.e. no progress bar.

The problem here is that it’s specifically kernel_task that is the problem:

  1. It’s difficult to know what it’s doing.
  2. Restarting the machine might well make things worse - if it causes kernel_task to start over.

I think the only thing to do is to just wait for this activity to complete. But after a few days you might have to restart anyway - and hope for the best.

BTW there still being data in the swap file isn’t necessarily an indicator of a current problem. Until those pages are needed they’re probably going to stay out there - even if memory became plentiful.