iMac slows down after Big Sur installing

Same thing here, I updated my iMac 2017 from High Sierra to Big Sur and everything went slowwww as a snail. The boot time is terribly slow and I'm seeing frequent spinning wheel when I'm working with Adobe apps such as InDesign as the file name's appearance takes time to load. It's a mistake that I shouldn't upgraded my mac because everything's fine with my High Sierra, and the Big Sur should namely as a Big Mistake. Now I'm thinking of downgrading because I can't work because of the frequent lag. Well, gonna use my Windows PC to continue my work and thinking I'll just erase the Mac's drive and install back the High Sierra again.

Unlike Windows, Apple's frequent OS changes makes their recent Macs obsolete. Thanks Apple!

I bought an external SSD for my 2017 iMac, found an easy to follow Youtube video and it has sped up everything on the Mac. Boot up times went from a couple minutes to around 20 seconds. Opening an app went from around 30 seconds to about 3 seconds. Everything on my mac now runs tremendously faster. It’s sad that my $1,100 machine was so slow but my $80 fix has made it enjoyable to use. I now love my machine and didnt have to open it up or take it to a repair person. Some places were quoting me $400-500 to open it up and add SSD internally but the $80 Samsung SSD took about an hour to install following the Youtube video and didn't compromise the iMac in any way. My family and I own iPhones, iPads, iWatch, an Apple TV and this was my first iMac. I was sad with the speed to say the least but next time I know to get the model with SSD.

Upgraded my MacBook 12 2015. Now, it's completely unusable and super slow. Firevault is turned on. Subjectively, when I had Mojave installed, everything was 2-3 times faster. I regret my decision to upgrade... I did it only because I wanted to test new apps in App Store. *******.

*******!

SAME HERE! OH GOD ITS SUCH A RELIEF KNOWING YOU GUYS ALSO HAVE SAME PROBLEM LOL. Jokes apart! Bought Brand New iMAC 2019 4k Retina and its SO SLOW on BIG SUR!!!! Cannot code or use Xcode at all!! All the time BeachBall keeps on coming and loading! SO FRUSTRATING! I was thinking of throwing the imac away!

Please can anyone tell is there a fix to this problem??

Lots of complaints over slow Big Sur upgrade - in this case iMac 27" 2017 24GB 3.4 GHz - impossible to use after upgrade installation on fusion drive, same if clean install on external thunderbolt SSD - had to revert to Catalina - no explanations yet?

I have iMac (Retina 5K, 27-inch, 2019) and since installing Big Sur my boot times have increased by at least 300%. For the first 5 minutes after boot my iMac is unresponsive and any attempt to start an app takes around 5 to 10 minutes. I rebuilt the fusion drive and performed a clean install of Big Sur and this made no difference. My iMac is less than a year old and is almost unusable.

My Activity Monitor shows my system at 90% idle so I have no idea what is causing the poor performance.

Very simple. Either macs are dogs and we've all been sold a bill of goods or we're all weenies cuz everyone knows nothing ever goes wrong with macs.

This is ridiculous, but has anyone contacted some Apple technician to find out more or if will be soon another update to improve this abortion?

Is there a definitive answer to this irritating issue of slowness (to the point of not being usable ) on Big Sur. I'm so angry that Apple are not fixing this and there is no communication that I've seen.

Yeah i'm wondering too. Is Apple ever gonna address this? I won't upgrade to Big Sur until i'm sure it won't slow down my iMac again.

I’m literally going insane with big sur:(((((((((

What's the latest on this issue of Big Sur slowing down iMac Pro's? I'm running a late 2019 iMac Pro, 10 core, 64 GB RAM, Radeon Pro Vega 64X 16 GB, 1tb, still running Mojave. The "upgrade" to Catalina caused crashing, slowness and wasted time, so I rolled it back to Mojave and have not had any issues. Should I stay with Mojave or perform the upgrade to Big Sur? Thanks

The exact problem happened to me and is still an issue. I have a 2017 iMac 27 inch. 40GB ram and a Fusion 27 hard drive. I also have a 15 inch MacBook pro. I updated both of them on the same day to Big Sur. My laptop has no issues but my iMac takes almost 10 minutes to startup. It is May 6th and I have not found a fix yet. I re-installed Big sur but the same issue. I am going to try and go back but I fear that the Big Sur upgrade (ya right ) has messed with the fussion drive.

Is there anyone who hasn't experienced this problem? Anyone for whom the upgrade has gone just fine?

Are there any particular circumstances in common with these experiences?
ie. Is Big Sur also horribly slow if you do a clean install?

I have an iMac 2015 and am considering upgrading, but not with thee reports.