iMac slows down after Big Sur installing

Question

Created Jun ’20

Replies 180

Boosts 0

Views 62k

Participants 168

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

Boost

Answer 1

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

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

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

Answer 6

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

Answer 7

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

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

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

Answer 12

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

Answer 13

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

Answer 14

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

Answer 15

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