iMac slows down after Big Sur inst… | Apple Developer Forums

Hello!
I downloaded the macOS Big Sur image on MacBook Pro, then installed, everything works fine.
I started downloading the macOS image on iMac, but at the end I constantly got a loading error. Then I install image on USB from MacBook and installed it on iMac. After installation, iMac began to slow down, for example, it opens a folder in a few seconds or or launches the browser in 10 seconds.
With what it can be connected?

iMac (Retina 4K, 21.5-inch, 2019)
Serial Number C02Z1085JWDX

macOS

58k

Posted by

Kirill1104

Hi! I have an iMac27" late 2014 and after I installed Big Sur 11.4 my system with 32GB of RAM and this (shit!) Fusion drive system is come really really slow... until to 15/20 min to lanch an app!!! And I think with the next versione of macOS 12.x it will be definitly "dead" for Apple... so I decide to remove macOS at all and try to install Ubuntu or other GNU/Linux based distro. I am an Apple user from 1995 and this make my really un-happy... No good solution I have found to solve this issue, the only one seams to be just only change internal drive with a full SSD disk (pity this means 3/400 Euros...)

—
FScarfato
I have 27” imac late 2014 i7 cuad qore turbo ram 32g with frigin fusion too. 3tb. The best part is only 128g is ssd. Balance is hdd.definitely not obsolete yet with fast moving tech. Just like cr7 n messi. Still relevant. anyway. Same prob. Mac os big sur slow. Apple consider our mac is vintage. My solution, i drop fusion. Keep the 128 ssd bought new 500g ssd. Partitioned. Then reformat to mac os catalina. This is the way! This is the way p/s convert hdd to externals. N set up NAS. Network attached storage. Wireless. But lagging when accessed

—
Hilmi21_zul
Clearly Apple has gone to the dark side with a nasty update. You know they know (if we could only get an Apple employee on the OS dev team to speak LOL). They made an update that's good for some models (and their profit margins), but destroyed perfectly good computers with a dirty move. I am furious with this I'm not buying another mac ever, because somewhere in the near future I'll face the same putrid ***** because of another lame thing they do for their profits. Windows/bootcamp are my future

—
dreganism

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I'm sharing an iMac Late 2014 (the oldest computer that is said to work with Big Sur)

It was very slow so we fully wiped the computer and installed a fresh copy of Big Sur, and it was still very slow, laggy etc.

We left the computer on doing nothing for 2 days and now it's fully fast as it was before - there are 2 days of background update processes that the mac doesn't tell you about...

Posted by

pushka

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Did the iMac Late 2014 have a fusion drive?

Posted by

brerlappin

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Late 2015 iMac with fusion. Don't want to upgrade to Big Sur reading these reports. Anyone else see the issue go away in a few days as was the case for @pushka?

Posted by

kimardenmiller

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SAME PROBLEM I have latest iMac 27-inch, 2020.. it has 1tb flash drive (ssd) and 64gb ram. It was lightning speed in everything, booting up took literarily 6 sec. on BIG SUR until the recent update 11.4 (20F71).. it's all slow now !!! I suspect this new update might benefit the new m1 chip and create some issues with current intel chip processors.. hope they will read this and fix it with another update.. Even if you factory reset the imac and install a clean Big Sur it will probably be downloaded with this new update..

Posted by

ChrisHeart

Having exactly this issue.

Upgraded my iMac 2017 (27 inch, 8Gb ram, fusion drive) to 11.4 a few days ago and it's been a total disaster. (11.1 was running fine before this.)

Initial upgrade was slow but seemed to go okay. However, after a few hours and waking from sleep overnight, computer was running really slowly. I then restarted and after that the computer wouldn't even start. Spent hours trying to reinstall OS etc with no improvement.

Spoke to Apple via chat, and they were useless. I was promised a follow up phone call that never took place. Eventually I resorted to installing the OS on an external drive so that I could get into my computer and backup the few files that weren't synced to my iCloud.

I then erased the internal HD and reinstalled Big Sur, hoping that this would fix all the problems, and give my Mac a (probably much needed) clean out...

However, since erasing the HD and reinstalling 11.4 it's still running at an ununsable slow speed. I've left it on for hours to allow it to sort itself out, and it's making little difference so far. Very disappointing. What's it even doing that is making it that slow? There are very files on the machine now.

Why have Apple done this? Before this it was a very fast computer that coped running multiple apps at the same time (logic, photoshop etc.) without any obvious issues.

NOT COOL - it was an expensive machine.

—
mkanedog

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Same problem. Recently bought a new iMac 21.5 inch, 2017. It was doing well on Catalina. Then upgraded to BigSur and it is the worst experience I ever had in more than 30 years using Mac. Slow as hell.

And nobody from Apple has wrote a solution to this issue???

Posted by

paul darky

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The only solution that worked for me was to uninstall Big Sur and run my macOS on Catalina. I have a 2018 Macbook Pro. Never any issues prior to installation of the new OS. I installed Big Sur as soon as it came out. Does anyone have an update?

Posted by

kimeebear

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Damn, guys, can you please fix THAT SH*******!!!!!! I have to work with this FA******* MAC!!!!!!!!!

Posted by

juragermanyuk

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Someone on Reddit claims the 11.5 beta is faster with fusion drives. Fingers crossed it really is.

Posted by

brerlappin

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HOPE

Just wanted to add to this thread and say there is hope, because I thought there was going to be none after I installed Big Sur and waited for days.

I installed Big Sur (v 11.5) a few days ago... install took a few hours and then my system slowed to an absolute dead crawl. Pushing one key on the keyboard would result in either nothing or multiple key entries... a patient and slow key press finally got me logged on to my user account (there's only one)... once there, my mouse would take ~2-3 seconds to respond, was jagged, laggy, overshot the destination - in other words, impossible to control, as if every system resource was maxed out... mouse clicks were super problematic, non-respondent and delayed... the system was almost unusable.

I read comments in this thread, saw that lots of others were experiencing similar problems... I told myself to wait a day or so to see if some background processes were still resolving... all the system resource apps (Activity Monitor, Sys Info, etc) showed almost no resource usage, which seemed strange, so I waited. For two days... nothing changed... sys was still bogged down...

Woke up this morning. Checked Reddit, saw someone mentioned to reset the Systems Management Controller (SMC) by powering down and unplugging for 15 seconds and then powering back up. Check here: https://support.apple.com/en-us/HT201295

I powered down, unplugged and then for added good measure, unplugged all of my external drives (someone had mentioned USB controller issues, too)... it worked like a charm and true to some other posters I've seen elsewhere - the system feels faster than it ever was...

HUGE sigh of relief...

My sys specs:

iMac (Retina 5K, 27-inch, Late 2015) Processor 4 GHz Quad-Core Intel Core i7 Memory 32 GB 1867 MHz DDR3 Graphics AMD Radeon R9 M395X 4 GB

Good luck! Hope it works for you, too.

Posted by

JayBizzle

@JayBizzle - but do you have a fusion drive? I think that's the big deal here - Fusion Drives aren't working well with Big Sur

—
iwbyte

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System: MacBook Pro (16-inch, 2019), 64 GB RAM, Elgato Thunderbolt dock, Apple Pro Display XDR

Symptoms: Delayed text while typing, sometimes lost characters, major lag when changing volume or switching Desktops, Thunderbolt dock was often not recognized without connect/disconnect cycling, Sound settings (Speaker/Mic) not retained, Camera not connecting. Much of what you've read on the other 11 pages of this issue. Many restarts, Bluetooth resets and the like.

Prescription: Read JayBizzle's post above. Reset the SMC. See here: https://support.apple.com/en-us/HT201295

Result: MBP is back to running smoothly like in MacOS Catalina. Thanks JayBizzle.

Posted by

JB_SDNM

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I’m definitely gonna add to this!! So I purchased my 2019 27 inch iMac (16 gigs ram) in middle of 2020. I use it strictly for recording and mixing music. So there’s hardly any other apps that I’ll open besides Logic Pro x, or maybe watching Netflix and streaming services every now and then. it was working OK when I was using Catalina, but then … I downloaded Big Sur 11. And everything went down the toilet, it started stalling for five minutes before it would even turn on. And even when it did I noticed a HUGE Change in performance when it came to opening and using Applications. Including my recording software. This is a brand new computer keep in mind, that I paid very good money for. So of course I’m gunna complain. I called customer service about eight times for the same reasons and they could never give me a clear answer on what to do (understandable) not everyone has all the answers. So I ended up eventually taking it into my local Apple store with an appointment to get it looked at. All they could tell me was they’re going to wipe out the entire computer and erase everything and start from scratch. That was a “Apple Genius” saying that. Which I said was fine, they did that and the problem still preceded. I know it has something to do with the updates. My fear is they created these updates on assumption that everybody is switching to the Apple one chip and moving away from Intel. I feel like they geared these updates to cater only to their Apple one chipped computers. I could be wrong but a part of me feels like I’m absolutely right!! This is ridiculous we all paid a hefty penny for these computers and they’re already throwing them out the window it seems like. But lets hope they do something about this!

Posted by

Tbibi805

Apple clearly lost interest in customers they already have. I bought a Mac Pro setup in the 10k region and my mouse sometimes glitches, somehow i get the strangest GPU errors when showing the 'latest' in iTunes ... things like that.

I would suggest to fine large companies (more than 10M installations) for buggy updates as it is the only incentive they would have to quit this sh .... strategy. They should pay for customers losses up to 70% of the purchase price of the whole thing.

—
Schwaller

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Apple does not care ... there's no money in it.

Posted by

dreganism

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iMac slows down after Big Sur installing

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