iMac slows down after Big Sur installing

Same here, I updated my Mac which I purchase on 2017 and was sold a 2015 so be careful... and they then make us update and then my computer is acting stupid. Slow as **** and they say it my fault. When its clear they are responsible of this problem. My computer isn’t full at all I have so much space and I did everything they’ve been asking and now they get to just clean there hands?

What a mistake. My MB PRO is spinning for a few hours to open a web browser. I have to go back to Catalina. Is there any way to go back without data loss?

I have an iMac 2014 5k with 32 GB Ram, The system can't manage the memory. most of the time I have 4.3% to 12% free memory. And the speed is so low for simple tasks.

If I can help somebody I just would recommend NOT to install Big Sur, again, if you have doubts DON'T DO IT, it will tear apart your mac/iMac

I have an iMac Late 2014 with 32 GB RAM and 1TB SSD hard drive that worked perfectly until I updated to Big Sur

Things that happened after installing big sur:

• OS Boot delayed: From 10 seconds to more than 30, some times even more than 1 minute

• Terribly slow: After Big Sur, opening just one program slows the computer, now I can't use iMovie and any other software because the computer collapses

• Permissions issue: After updating I had several issues with permissions, I couldn't write to folders I did and more important, I couldn't use the System Preferences because it said my user wasn't admin, I've been using the same user for more than 6 years.

My iMac is utterly unusabled since the Big Sur updated. It can't handle simple daily tasks like coding and emails without grinding to halt, and takes about 10 minutes to reboot after it crashes.
Great work Apple this is the worst update in history, you have surpassed Microsoft finally at something.

I especially love the fact you've brought back that old feature favourite 'the spinny wheel of death'!! I'm equally impressed by the general OS responsiveness that puts catatonic mummified pharoe's to shame.

I've experienced problems with endless lags and the spinning wheel with Mail (when trying to quit), Safari (when trying to open a new tab via keyboard) and other apps when trying to quit and also when trying to start them. The issue is really annoying since the only solution seems a long press to the power button to switch off the unit.

The update to 11.2 and 11.3 beta didn't solve the problem. Sometimes the problem disappears for several hours and then returns again on both my iMac 2019 and my MBP M1 2020.

Same problem here. I had Sierra OS 10.12.6 and it worked beautifully. But I needed to installed Office 365 so had to update. Called Microsoft and they walked me through the update and they chose BigSur. What a mistake. It is soooooo slow plus I have to keep putting in passwords and getting texts to verify. What a pain. How dumb of Microsoft, full knowing that there were problems with this update. I could have done Mojave or Catalina.

Now what do we do, are we stuck with this update and can we downgrade?

2017 Macbook Pro 15" was running fine with Catalina. Big mistake to upgrade to Big Sur, everything went south since. Computer is very slow, I see the spinning wheel a lot. Very hard to work like this

Hi,
I have been using MacBook Pro 2016 since 17-07-2017 without any problem. Suddenly a week ago (feb-2021) a problem appeared with its screen, that it turns off after 40-45 degree extension. I checked it on Apple site and found it is a common problem called Flexgate problem and my Mac version is involved.

Now i am using it on external screen because official Apple service in Erbil, Iraq declined to fix.

I also updated it to Big Sur and have two other problems with it: first, apparently the Mac has gotten slower in its processing which is bothering. Second, i was forced to use google chrome instead of safari which i preferred before, because safari does no longer load any web page (not even google search).

This is about my Mac:
MacBook Pro
2 GHz Dual-Core Intel Core i5
8 GB 1867 MHz LPDDR3
Macintosh HD
Intel Iris Graphics 540 1536 MB
C17SN40DGVC1

Kind regards,
Reben Darweesh

Same here! macbook pro 2017 non TB
I need to solve it or I have to go back to Catalina.

Agree, I bought a brand new iMac 5k 2019 in the summer of 2020 and it was super sprightly until I installed Big Sur and it’s super slow to boot and sometimes tediously slow just to use. I created an external SSD boot drive and installed 32gb of ram and it takes 52 seconds to boot up!!! What the hell!!! I’ve got a 2009 MacBook that boots quicker Han this 6 core i5. What’s going on apple???? Very poor show.

Unfortunately I too have the same problem! I have MacBook Pro(Retina, 13-inch Early 2015) 2.7 GHz Dual-Core Intel Core i5 with 8 GB 1867 MHz DDR3 memory and Intel Iris 6100 1526 MB Graphics, not too fancy, but still a great computer until the last update to the Big Sur... reminded me how my all my iPhones slow down when they get their 2nd or 3rd update.... Apple why are you doing this to us. We will buy your products, just not as often as you want us to.

OK.

I've found three things that seem to really cause big problems with 'Big Sur'.
The first is if you have a Wacom driver installed. This seems to completely ***** the boot, Many minutes delay at boot. Answer here is to remove the driver and install 'afresh' (don't 'upgrade').
The second is certain anti-virus programs. Again remove, and install afresh. It seems that the driver they use to connect to the filesystem during boot, doesn't upgrade correctly, and has issues under Big Sur (a few like Avast, don't seem to work correctly even with the latest version).
The third is large numbers of external drives. Something seems to go wrong with the USB handling for these, with lots of USB stall messages during boot. Now what is strange here, is I added an external USB3 powered hub, and now boot with this switched off. Once the system reaches the login, turn it on. Lo and behold, boot in under 20 seconds, versus over 5 minutes!. The drives all work perfectly.
It appears that something in the USB/filesystem checking during the actual 'boot' process goes wrong when there are more than a certain number of drives attached. Attach them after boot, and it works great.
Reinstalling the Wacom driver, and switching the drives on after boot, takes the boot time down by about 15 times. The system also then seems to run properly. Things open quickly, and don't glitch. Except for a few packages that don't run completely right, the system is now usable again.

Same problem here with a 1 1/2 year old iMac 21.5 Retina 4K with a 3.6 GHz i3 and 16 GB 2400MHz DDR4. It is so slow to boot up that it takes almost 4 minutes (My Windows 10 machine with a similar amount of Ram and a similar Hard Drive takes less than 1 minute). Just opening mail takes 3 minutes and same with any other application, whether Apple or third party and I am constantly looking at that spinning colour ball. Everything is so slow that I am seriously thinking of giving up and changing everything over to my windows machine. I have owned 5 Macs for the past 20 years and this is the worst operating system I have ever encountered, including on all of my windows based machines. Steve Jobs would never have let crap like this out of the building.

I'm having the very same issue with my 2015 imac. I was low on RAM and increased it to 32gb and my CPU is operating fine. But on start up I'm finding first that it takes a few minutes and when trying to open apps I not only get the spinning wheel I also have messages that I do not have permission to open that particular app or that the app isn't responding. Sometimes it crashes altogether. This has all happened since the Big Sur update.

Exact same problem as all others with iMac & Fusion Drive. (Late 2017, 27" 5K Retina, 24GB Ram upgrade). Its running slower than the 12 yr old macbook pro it replaced....was brilliant on previous OS which is the really annoying thing.

Upgraded a couple of days ago to 11.2.2, and now machine is 90% back to Catalina boot speed!.
It is a tiny bit slower to the first part of the slider bar showing, but literally only a second from there to actually being booted.
Hurrah.
Hope other people find the same improvement.

For what it’s worth, same issue here with a 2015 iMac. Boot time is more than 5 minutes. Even after logging into the user account it still takes several minutes to get to a responsive desktop, with the dock, menu bar, background appearing one after the other, the screen going black, mouse not responding, etc. This is like a time travel experience back to Windows 95.

Once the desktop is up and the first apps are launched, the machine runs fine. Maybe a bit slower than Catalina (which can be expected with a new OS).

Appalling— slowdown still happening after last 11.3 beta update. This problem still remains months later

I am here with the exact same problem. Typing is laggy, I look at the spinning rainbow ball multiple times a day now when I have never seen it come up on this computer before. I have a 21.5” iMac mid 2017 Retina 4K, i5 with 8GB ram that has never struggled to do anything which now takes a decade to even turn on and then once it turns on, further time to even become usable. Appalling this hasn’t been fixed

Updated last week and same is happening for me (iMac 5K 2017). I got rid of my iPhone for this same reason, and hate that it's a pain to go back (if not almost impossible) to previous OS, when all I need is my devices to continue working as they were before, I mean like a day before updating. I already managed to get my hands on an NVIDIA GPU to say goodbye for good to Apple. I haven't got an exciting update in the last decade, all the oposite.

Hi, I had exactly the same problem but it seems to have been fixed (as somebody else mentioned) by uninstalling my virus protection software [Avast] and re-installing it.

Hope this helps!

I have the same problem with a iMac 27" (end of 2015).
I made a clean install of it but the problem still remains.

After Troubleshooting and updating a brand new iMac running BigSur 11.2.3. iMac would perform fine and then user would report sluggish performance specifically using adobe photoshop and indesign, during shutdown the bigsur image would hang and present with a divided color tone straight down the middle. Profile was originally migrated from an older iMac using the migration assistance. Tried creating a new profile and moving the files there which worked for a little bit, but the problem reoccured. As a final effort I reformatted, performed an SMC reset and NVRAM reset and handed it back to the user. He said it was working perfectly for the morning and then it began running slow again. The only difference was he connected to his synology NAS, as soon as he ejected it everything was working fine again. I hope this helps some of you. I'm not sure if its all externals or just network shares but that seemed to be the constant for us. At all times after set up the user either had the NAS connected or a usb external drive. Try ejecting any drives you may have or performing an SMC and NVRAM reset, (I'll note too Apple support instructed me to simply boot into safe mode, sign in and restart. I'm not sure the mechanics of this but they stated it does fix a number of odd problems for some reason).

iMac (Retina 5K, 27', 2019)
macOS Big Sur 11.2.3

Finder and disk operations very slow.
After ejecting my Synology NAS drive, everything went to normal.
It seems a problem with network drives.