iMac 2017 starts too slow after upgrade from Catalina to BigSur

Notes:

• Delete CleanMyMac.
• Delete Avast (if installed)
• Delete NordVPN, unless you REALLY need it.

Then,

• Reset PRAM: Reset NVRAM or PRAM on your Mac - Apple Support
• Run First Aid: How to repair a Mac disk with Disk Utility - Apple Support
• Startup in Safe Mode: How to use safe mode on your Mac - Apple Support

Cheers,

Jack

Hi there,

I believe we need to proceed with an EtreCheck report. EtreCheck is a useful app to diagnose and identify issues, both hardware and software. It is trusted by many users. Please follow the steps outlined below:

1. Navigate to: https://etrecheck.com and get the free version of EtreCheckPro.
2. Download it. It is a free and trusted app. It is often recommended here on Apple Support Communities. 
3. Open EtreCheck, and before running the report, be sure to check “Allow full Drive Access” at the bottom of the EtreCheckPro window.
4. Run the report, and put it in a post, as seen here - https://discussions.apple.com/docs/DOC-250000211. We will then examine the report for issues in your Mac.

Cheers,

Jack

We could try doing an entire erase and reinstallation of macOS Big Sur. However, this can only be done if all your files can be backed up to an external hard drive. To backup, "copy and pate" or "drag and drop" files you want to save. Do not use Time Machine. This will just restore issues.

When you are ready to erase and reinstall, follow this guide:

1. Verify all your data is backed up to an external hard drive using "copy and pate" or "drag and drop".
2. Sign out of your Apple ID in System Preferences > Apple ID > Overview > Sign Out.
3. Shut down the Mac.
4. Turn on the Mac, and immediately press and hold Option + Command + R until you see a spinning globe.
5. Once you are in macOS Recovery, verify you are connected to WiFi in the top right corner.
6. Go to Disk Utility.
7. Select "View" in the toolbar > "Show All Devices".
8. Select your main hard drive. This will either be "APPLE SSD...", "APPLE HDD...", or "Fusion Drive".
9. Click Erase, and input the following exactly: (If you cannot select erase on the main hard drive, erase the "Container".)
10. Name: Macintosh HD
11. Format: APFS
12. Scheme: GUID Partition Map (if shown)
13. Click Erase
14. Quit Disk Utility
15. Go to the reinstall macOS app.
16. Follow the prompts, and install on Macintosh HD.
17. Once done, setup your Mac, again, and once setup, drag and drop or copy your files back to the iMac.

Cheers,

Jack

That is Catalina Recovery Mode. How did you get to the Big Sur recovery earlier in the troubleshooting steps? Whatever you did there, do that and resume the steps. Also, in your case, you will have to erase the "Container".

Cheers,

Jack

My iMac 2017 is running slow.

Hi Jack,

My iMac 2017 is running slow and Im looking for solutions.

Thank you Jack! I did run the report and I think it appears fine

Hello,

I have similar issues and ran a report.

Will adding RAM solve my issue or is that necessary as the report found no major issues?

Please advise,

Thanks,

Gordon