iMac slows down after Big Sur installing

App & System Services Core OS
Kirill1104 OP
Created Jun ’20
Replies 180
Boosts 0
Views 59k
Participants 169
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
Replies  180
Boosts  0
Views  59k
Participants  169
Jodec OP
Aug ’20
Hello!

Same here MacBook Pro everything works fine. iMac late 2015 1TB Fusion Drive is very slow. Startup takes very long too.
1
filip.petkovic OP
Sep ’20
Same with my iMac, startup is very slow and apps lunch much slower after installing Big Sur.
It's probably something with fusion drive and how Big Sur use it. Hope they will fix it :/
2
twmuse OP
Sep ’20
Same here on 2019 iMac, tried on Fusion Drive and also external, same results, extremely slow startup and app opening. At this point not usable at all.
1
mp_72 OP
Sep ’20
Same experience. Even I am on quite old comp (iMac (Retina 5K, 27-inch, Late 2015), its still 60-70% slower then on last Catalina version. Startup, App loading. Safari is the worst, takes about 10-15sec to start loading pages - but before it says I am not connected to the internet. Same on my MBP 2018.
1
bpprodanov OP
Nov ’20
Hello,

Yesterday I installed the official Big Sur release on my iMac (2020, 5k 3,8 ghz, 2 months old) and I see a huge slow down in performance. All the problems mentioned above. Also when I input text in Safari or Spotlight the letters come too late after I press the keyboard button. There is a huge lag in writing, also opening images or websites!
2
anthonyhoward OP
Nov ’20
I'm having the exact same issue as everyone else on this thread. Startup is very slow and choppy. It also takes about 5 minutes to load a project in Logic Pro X using minimal resources. It's almost unusable. Hoping they can fix this soon.
3
TeraBit OP
Nov ’20
Hello, I am on a iMac 27" 2019, is really slow, it should be a joke, but even write this message took me around 40 to 70s, cause it lags with just writing on an input.
4
Enryfox OP
Nov ’20
iMac 2015 with Fusion drive: after installing Big Sur 11.0.1, startup is painfully slow. At least three to four times slower than 10.15. It seems as if it is reading everything from the rotating HDD instead of the SDD portion.
After boot is complete, apps are then pretty snap and speed is back to normal.
1
PremedPablo OP
Nov ’20
Same here with my iMac, especially the dock, it animate very slow, it locks too much, even when blur is off.
2
alejandrosejas OP
Nov ’20
Yes, exactly the same performance issue. I have an iMac 27" Late 2017, and the boot went smoothly UNTIL I upgraded to Big Sur. Big Sur has made my computer boot extremely slow. Apps also take lots of time to load.
2
mikeru OP
Nov ’20
I have an iMac 27" Late 2017 too. Since I installed Big Sur, it takes ages to boot and load any application... Until last week my computer run smoothly.

We all seem to have the same issue, so it's most probable that Apple will make an effort to find the source of this problem. Let's trust them as always.
2
lenineto OP
Nov ’20
Same here guys.
Just installed official Big Sur update yesterday on my Macbook Pro 16" 2019 and the lag on typing is just unbearable.
I've disabled that accented character popup, changed my key repeat to the max but still, very noticeable and annoying lag when typing.
Anyone found a solution yet?
2
Papanoos OP
Nov ’20
hello :) I have installed big sur on my iMac, and it became super laggy. I started the installation on the mac mini and fortunately it didn't have time to complete so I cancelled it. in my experience, installing Big Sur now is a BAD IDEA.
2
simad4sx OP
Nov ’20
Hello! I have 2019 iMac 27 with 24GB ram, and i have upgraded to macOS Bigsur yesterday and it's slowed my mac totally! It need about 10 years to startup system, about 4 seconds to startup safari. But in safari, when browsing, everything is smooth and super fast like usual. Just think there will be another update very soon to fix this problems with starting up.
1
tnctan OP
Nov ’20
Hello! I have 2019 iMac 27 with 16GB ram. take very long to startup, after the long startup, the overall speed are ok.
1
AndreyKitaev OP
Nov ’20
Same problem with iMac 21,5 2017, started right after the Big Sur update, can't believe they let this happen in official release 😞
1
sanitariu OP
Nov ’20
I have the same problem. Using MacBook Air 13 inch (2015). I think the problem is some sort of nvme/ssd putting to sleep too often or snapshotting current memory on ssd/nvme then resume from there.
After restart or resume safari and other apps needs a lot of time .... like everything is frozen for 20-30 seconds even typing password at screensaver !
Catalina was super fast ! At least 2 times faster. Wonder if i can go back from my Time Machine ?
Problem is that system firmware was also updated .... and the problem may be there too ?!
1
Lip_art OP
Nov ’20
A similar problem. slows down graphics, scrolling, animation.

lags when typing and erasing text, lags in any applications, especially noticeable when scrolling through pages in safari.
MBP 13 2020 i5 16gb-ram
1
mimagast OP
Nov ’20
Same here on 2019 iMac 27", i5 3GHz, 40GB ram. The boot process has slowed down enormously and the loading of the programs after login takes significantly longer.
1
Mike123456789 OP
Nov ’20
Help Apple, please! Update as soon as possible!
1
VivaceNonTroppo OP
Nov ’20
MacBook Pro (Retina, 15-inch, Mid 2015)

2,2 GHz quad core Intel Core i7
16 GB 1600 MHz DDR3
Intel Iris Pro 1536 MB

And can't f*ing scroll the pages fluently or change desktops fluently after Big Sur update.
Even my Visual Studio Code which used to work perfectly before the update is clogging now.
Why would you do that to your clients, Apple? Is it again like with the iPhones where you had to admit you were slowing them down just to force people to buy new? This MacBook is worth more than two average salaries where I live, this is completely immoral.
1
NewMacHater01 OP
Nov ’20
My MBP is brand new (2 weeks old) and I accidentally updated from Catalina to Big Sur. what a disaster. all animations, scrolling typing video is disastrous now. this is the most buggy crap apple rolled out.....ever. typing these lines is already painful. do the apple clowns have absolutely no shame? I use macs for work, but now have to consider switching . Apple has totally lost it and now they are loosing even the most faithful mac lovers. bug fix? ever? customer support?
1
ttelmah OP
Nov ’20
For me, it is not bad when running, but the boot is appalling.
I have a 27" 2019 iMac Pro, with 64GB, and a 4TB SSD. Previously it took about 22 seconds to boot (slightly longer than my 27" I7, fusion), but now it takes over five minutes to boot.
It is the section from about 40% to 50% in the progress bar, it just stops and walks forward at a tiny fraction of a mm/minute.
The I7 conversely only takes perhaps a second longer. It's as if something in the boot doesn't actually like something about the Pro.
Once it has booted it almost works OK. Just a couple of applications with issues.
2
chsasidhar OP
Nov ’20
Same here after upgrading to Big Sur, the boot time increased and I regret doing the update. Apps are also taking time to load.
Terminal itself is taking time to open :( . I have imac 21.5, 2019. Apple please do something about this.
1
saboo OP
Nov ’20
Painfully slow boot times since Big Sur Installation.
Mac (Retina 5K, 27-inch, Late 2015)
Once everything everything loads it works fine.
1
iMac slows down after Big Sur installing
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