2012 Mac book pro runs really slowly

Most likely your original Apple hard drive is worn out or failing. I highly recommend you make a good backup if you haven't done so already. Replacing the hard drive with an SSD will greatly improve performance of this laptop.

You can try running the Apple Diagnostics. Unfortunately the diagnostics do not detect most drive failures. EtreCheck will sometimes be able to identify a bad hard drive.

You should always have frequent and regular backups.

Hi Monica17Bol,

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.

Also, Macs run "macOS", not "iOS".

Cheers,

Jack

Compipe_77 wrote:

Since I installed Catalina My Mac is no good any more, It is to slow to work with. Need help to go back to my old IOS version.

There are several reasons you Mac may be slow now. First macOS Spotlight will spend lots of time indexing files after you upgrade macOS to Catalina. I just upgraded my Mac today and it ran really slow with the fan running at high speed for a long time even though I am using an SSD (confirmed it was the Spotlight service). If your laptop is using a hard drive, then this process may take much longer.

If your laptop is using a hard drive, then the hard drive may be worn out or even failing. An OS upgrade can definitely put a lot of stress on an old hard drive. You may also have a software issue. To look for possible software issues run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper. To check the health of the drive run DriveDx and post the report here using the "Additional Text" icon which looks like a piece of paper. It would be best if your created your own thread so that we don't get confused here for the original poster.

To go back to the previous OS you must perform a clean install by first using Disk Utility from within the installer and erasing the whole physical drive before reinstalling macOS and restoring from a backup made before you upgraded to Catalina, otherwise you will need to manually transfer your data to the new user account of the clean install of macOS. It is best to create a bootable macOS USB installer using the instructions in this article:

https://support.apple.com/en-us/HT201372

Since I installed Catalina My Mac is no good any more, It is to slow to work with. Need help to go back to my old IOS version.