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
StefKouf OP
Nov ’20
The same problem here!!
After the update to Big Sur my Mac gone So much slower🤯
iMac (Retina 5K, 27-inch, 2017)
Processor 3,5 GHz Quad-Core Intel Core i5
memory 40 GB 2400 MHz DDR4
Graphics Radeon Pro 575 4 GB

It takes such A LOOOONG time to open and be able to work!! It must be an update coming soon i REALLY want to believe !!
1
AdamPL OP
Nov ’20
The same problem wit my iMac 27 2017
After the update to Big Sur my Mac isSo much slower, it is lagging
iMac (Retina 5K, 27-inch, 2017)
Processor 3,4 GHz Quad-Core Intel Core i5
memory 20 GB 2400 MHz DDR4
Graphics Radeon Pro 570 4 GB
1
nikkim OP
Nov ’20
Same here! Updated to Big Sur yesterday, i have a 2019 IMac and its taking an age to load, the whole thing is shocking!! Reminds me of my old Windows XP.......get it fixed please apple, shocking a release is as bad as this! On the plus can go away and make something to eat when waiting for it...
1
innovationsmaker OP
Nov ’20
I have 2 macs - Macbook Air 2015 and iMac 21.5 4K 2017.

On the Macbook I had so much "others" files that I wasn't able to simply update the system to Big Sur, so I did a clean installation. On the iMac - I did a regular update.

The older and slower Macbook Air performs perfectly with the clean installed Big Sur and the iMac is slow as f***. I have experienced this same problem with the update from mojave to catalina.

So guys, it seems that the better option is to back up your data and just make a clean install. Its not that hard... For me as a software engineer(with all the additional software and sysmem tweeks I need for my job) it took me around 10h straight to get my system as it was.

Sometimes its better to invest some good 10h of installing everything from scratch, rather than loosing time in working on slow computer.
0
ttelmah OP
Nov ’20
After a long session this morning with Apple support, they have suggested I switch back to Catalina. The rep said that they were having a lot of problems with Big Sur, and it'd probably be several months before it was working properly.
What I've decided to do is add a small external SSD, and install Catalina onto this, and use this to boot. Then can test at intervals as updates come along for Big Sur, to see if it starts to work acceptably.
1
kenramirez OP
Nov ’20
Same here :( first load takes around 1 min, with catalina it took about 10 seconds.
0
Digiitalex OP
Nov ’20
Perform a clean installation iMac (Retina 5K, 27-inch, 2017) Big Sur working perfectly.
Radeon Pro 570 4 GB
0
jrpembe OP
Nov ’20
Same problem with 2017 iMac. Just upgraded to Big Sur. Now launching apps takes minutes as the icons bounce up and down. No indication in Activity Monitor of anything taxing the system. Tried to return to Catalina with no success. Used Internet Recovery Mode to attempt a clean install from scratch and I'm still having the same problem. Lots of spinning rainbow wheel and waiting, waiting, waiting.
1
ttelmah OP
Nov ’20
To the user saying the machine where they did a clean install is OK, after my initial problems, I did this. Reformatted , and did a clean install. The problems remained.
It seems to be some particular hardware combinations that are having problems. Possibly Apple did not get the proper beta testing done with Covid.
On a 2017 i7 Fusion machine, Big Sur for me runs fine, On my 2019 iMac Pro using an SSD, it does not. On the former it does not seem much different from Catalina. Boot is possibly one second slower, but programs run OK and really everything is fine. On the latter, I used to get faster booting 30+ years ago, loading using a tape!....
0
Domshia OP
Nov ’20
Ridiculous! 2017 iMac with fusion disk and 40Gb RAM boots slower than my 2012 Macbook pro with Catalina.The overall speeds looks fine, but the start... oh my.
Anyone have good resources on how to perform clean install and roll back from Big Sur -> Catalina?
0
MatushF OP
Nov ’20
I downloaded big sur on my 2018 mid spec MacBook Pro with touchbar and everything works Perfectly fine. Now that I’m back home I also wanted to update my 2017 4K 21.5 iMac. But it’s the same as all of you others say, loading takes forever and even something like starting Safari takes five seconds. I hope it really gets better over time.
0
sergioas OP
Nov ’20
My Imac has slowed down also. Not only in initial loading but my large files freeze photoshop and makes working with them impossible. This change was not immediate, however. Big Sur was installed a few days ago but I started noticing problems this morning. Perhaps there was an automatic update overnight. I have 48 gig of memory and my hard drives have plenty of space.
0
klaudio001 OP
Nov ’20
The same problem here!! 
After the update to Big Sur my Mac gone So much slower, it takes more than 2 minutes at the start-up vs Catalina 24sec!!!!
iMac (Retina 5K, 27-inch, 2017)
Processor 3.4 GHz Quad-Core Intel Core i5
memory 40 GB 2400 MHz DDR4
Graphics Radeon Pro 570 4 GB

Please fix this issue.... I feel like I'm working on Windows ;(
0
toxdesignro OP
Nov ’20
Same here :( windows style
0
hdnsameera OP
Nov ’20
Same here.

iMac Retina 4K, 21.5, 2017

  • 3.4 GHz Quad-Core Intel Core i5

  • 8GB 2400 MHz DDR4

  • Radeon Pro 560 4 GB

0
AndreyKitaev OP
Nov ’20
Resetting SMC and NVRAM helped! iMac started to boot as usual (about 20 sec) and all programs appear ultra fast. Hope this helps you
0
AndreyKitaev OP
Nov ’20
Forgot to say: to reset SMC on iMac just pull out the power cable and wait a little bit.
0
MiriamP OP
Nov ’20
It is embarrassing and frustrating to see a copy of a 3.7GB file to a flash drive in 43 minutes. My MacbookPro14,1 and an iMac19,2 are having the same problem. It's hopeless.
0
boydp182 OP
Nov ’20
Yeah, it's an absolute disaster. My boot up time takes almost 2 minutes just to get to the screen to type in password to enter the OS and then after that takes another 2 minutes to the point I can start using computer. I noticed dropbox takes forever to start up where on my other computer it boots up just fine.
The boot up time is definitely frustrating. I just couldn't believe it and overall it's just sluggish and takes 10 seconds to open a browser or another program and I have a 32gb ram, i7 imac with top video card.
I reset SV and VRram and it didn't solve anything.
I am very disappointed to say the least. It's embarrassing when windows boots up faster. I also only have one login item and that's dropbox only. I have hardly any extra stuff on my computer.
The boot up times from previous version went up 300% to 500%. It's just crazy.
2
Manpasand OP
Nov ’20
I am having a same problem, it looks I am working on a windows.
0
Vincentroger2000 OP
Nov ’20
Rule #1. Never download software update on your macOS systems. The main reason Mac proposes update is to slow down your Mac so you buy a new one.. My macbook air is 5 years old. I did not download any software update. It runs like a good well oiled machine. I was thinking of crashing rule 1 and download macos big sur blabla. Based on the messages posted here, I won't
0
vjalessandro OP
Nov ’20
same issue , ridiculous that Apple did not take any action so far . my imac takes 3 minutes to run normally
0
occurred OP
Nov ’20
iMac Pro from 2018.
Everything file related, or finder, is very, very, very slow and I‘ve to wait 10 seconds when opening e.g a file or directory within any software. It is so frustrating currently.
0
MazenTahhan OP
Nov ’20
Same here....
8‑core 9th‑generation Intel Core i9
64GB 2666MHz DDR4 memory
AMD Radeon Pro 5600M with 8GB of HBM2 memory
1TB SSD storage
16-inch Retina display with True Tone

i have the highest specs Mac Book Pro 16 with the highest modifications, and after i upgraded the OS to macOS Big Sur, my laptop become super slow, like it takes a second to open any random file, like images or text files.
i feel so disappointed of the new upgrade.
2
mdavern2001 OP
Nov ’20
Slow, slow, slow. Some apps now will not open and my trash will not empty. Horrible. I will never upgrade again.

1
iMac slows down after Big Sur installing
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