So a few months ago I upgraded my Mac to macOS Big Sur and these few months I have noticed that my Mac is running really slow, and the battery is draining really fast everyday, this is a pretty new MacBook so I don't think it have problems with the CPU or anything, so can anybody PLEASE teach me how to downgrade to macOS Catalina, I am a student so I use my Laptop a lot. Thanks! (BTW my Mac is currently running macOS Big Sur 11.0)
Downgrading is not simple. Some of your data will have been updated to work on Big Sur (such as your photos library). So downgrade, and those items won't work.
If you're happy just to set up your Mac by erasing the drive then installing macOS Catalina, then that is possible. But you will be starting from scratch (no photos, no non-Apple applications etc.).
The other possible option (and this I've never tried so can't confirm it will work) is to do the above suggestion and then run migration assistant to copy over your user data and applications but not the operating system.
Downgrading is not simple. Some of your data will have been updated to work on Big Sur (such as your photos library). So downgrade, and those items won't work.
If you're happy just to set up your Mac by erasing the drive then installing macOS Catalina, then that is possible. But you will be starting from scratch (no photos, no non-Apple applications etc.).
The other possible option (and this I've never tried so can't confirm it will work) is to do the above suggestion and then run migration assistant to copy over your user data and applications but not the operating system.
Have you run any "cleaning", "optimizing", "speed-up" or anti-virus apps on your Mac?
Download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.
Copy the report
and use the Additional Text button to include the report in your reply.
IMPORTANT:
Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:
Also click and read the About info to further permit full disk access.
Then we can examine the report and see if we can determine what might be causing the problem.
How to Downgrade to macOS Catalina
