Hello. My Mac is running very slowly and has been doing so for a long time.

Problem: Computer is too slow

Major Issues:

Q -  Hard drive too slow - The hard drive in this computer is too slow.

Q - Drives:  disk0 - APPLE HDD HTS541010A9E662 1.00 TB (Mechanical - 5400 RPM) 

A - Using a Mechanical / Rotational Drive will be slow not matter how clean of an Operating System the user has installed. 

Added is the fact the 5400 RPPM is slow at best and even with a 7200 RPM Drive it will never be as fast as an all SSD Drive

If the user wishes to extend the life of this machine and get the better performance - suggest in investing in a reliable Enclosure and reliable SSD for the enclosure.

Good start for above equipment would be www.owc.com

Install the Operating System Directly to the External Drive and set the External Drive as your Startup Drive  

System Software:

  macOS Catalina 10.15.7 (19H2026) 

Q - Time since boot: About 17 days

A - Usually a good idea to Restart the computer more often. It does clear RAM and other good thing behind the scenes 

Q -  CleanMyMac X.app

A - CleanMyMac claims and other victim. On these Apple Forums,  it is sometimes referred to aka “ BrickMyMac “

As pervious Contributor has already mentioned remedial action is needed 

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster and comprising the Operating System

Certain Applications maybe available on the Apple Apps Store - this only means the Developer is prepared to pay Apple a portion on each sale. What the Application may do to the computer is up to the User to check this out before purchase

Any of the below should be removed as per Developers Instructions

This will include CleanMyMac 

One may consider reading some of the many posting specific to this application and arrive at your own conclusions.

There has been sufficient advise offered, from more than one contributor, for the User to make an informed and educated choice what the next course of action is required for this computer.

I see that you've installed cleanmymac to try and help with your speed issue. but using cmm to solve an issue is kind of like using gasoline to try and extinguish a fire. you should uninstall it using the developer's instructions.

other than that, there doesn't appear to be any software that would be slowing you down.

but you do have a mechanical HDD. and to make matters worse, it's the slowest HDD that was available at the time. and after 7-ish years of use, it likely has gotten even slower.  if you really want to "speed things up", you might want to consider installing macOS onto an external SSD, and run the Mac from it. to implement that, please see this informative user tip: How to Setup and Use an External SSD as your Startup Disk - User Tip

MDG_1967 wrote:

Thanks Jeffrey.

you're welcome. :)

I already have a 1 TB Seagate backup plus portable drive with 750GB free space on it. Could I use that for running the macOS or am I better getting another dedicated drive?

well, I believe you would need to partition the drive to do that, which means erasing it. so IMHO, a dedicated drive would be better. in my application, I use two separate Samsung T7 SSDs, that each run their own, totally separate macOSes.

given the age of my Mac, should I upgrade the OS to something more recent than Catalina. I have a message on my Mac suggesting is should upgrade to Monterey.

I would definitely upgrade to monterey. I'm a firm believer that you should always run the most up to date macOS that the machine can run.

one further question, given the age of my Mac, should I upgrade the OS to something more recent than Catalina. I have a message on my Mac suggesting is should upgrade to Monterey.

thanks very much for your help.

but I need to add that if you are planning on staying with the mechanical HDD, it will run even more slowly on monterey than it does with Catalina.