iMac slows down after Big Sur installing

Same problem with iMac 21,5 2017, started right after the Big Sur update, can't believe they let this happen in official release 😞

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 ?!

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

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.

Help Apple, please! Update as soon as possible!

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.

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?

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.

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.

Painfully slow boot times since Big Sur Installation.
Mac (Retina 5K, 27-inch, Late 2015)
Once everything everything loads it works fine.

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 !!

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

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...

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.

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.