Sudden and painfully slow performance on a 2017 27" Mac.

You've installed a couple of the worst apps possible for Macs: MacKeeper and CleanMyMac. Both are considered to be akin to malware by most of the experienced contributors here.

First, there is no reason to ever install or run any 3rd party "cleaning", "optimizing", "speed-up", anti-virus, VPN or security apps on your Mac.  This documents describe what you need to know and do in order to protect your Mac: Effective defenses against malware and other threats - Apple Community and Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support.  

There are no known viruses, i.e. self propagating, for Macs.  There are, however, adware and malware which require the user to install although unwittingly most of the time thru sneaky links, etc.   

Anti Virus developers try to group all types as viruses into their ad campaigns of fear.  They do a poor job of the detecting and isolating the adware and malware.  Since there are no viruses these apps use up a lot of system resources searching for what is non-existent and adversely affect system and app performance.

There is one app, Malwarebytes, which was developed by a long time contributor to these forums and a highly respected member of the computer security community, that is designed solely to seek out adware and known malware and remove it.  The free version is more than adequate for most users.  

Uninstall MacKeeper and CleanMyMac according to the developer's instructions. Find Any File can help in removing leftover components of apps that have been deleted. 

Do the following:  

#1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support. 

NOTE: Safe Mode boot can take 2 -3 minutes as it's doing the following:• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

#2 - download and run the shareware app Find Any File to search for any files with the application's or the developer's name in the file name.  For the two apps mentioned you'd do the following search(es): 

1 - Name contains mackeeper

2 - Name contains cleanmymac

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

#3 - reboot normally.

Hi there!

If you think your Mac might have an issue, you can use this procedure to help gather information on your Mac which will help us troubleshoot your Mac’s problem.

To start, use this Apple Support article as a guide, Get system information about your Mac, and let us know what year your Mac is, the model, and what version of macOS you are currently using.

Next, please upload a screenshot of your Mac’s storage information. In the Finder, choose Go > Utilities, then double-click the Disk Utility icon. (Disk Utility is located in the /Applications/Utilities folder.) Alternatively, click Launchpad in the Dock, type Disk Utility in the search field, then click the Disk Utility icon. Once Disk Utility is open, take a screenshot of the information it automatically opens to, which will be your startup disk. Next, select View > Show All Devices in Disk Utility and select the top-level, non-indented, disk entry. In most cases, this name will be one of the following:

• APPLE HDD…
• APPLE SSD…
• Fusion Drive

Then, take a screenshot of the newly selected entry. Upload all screenshots here. 

Next, use Apple Diagnostics to test your Mac to help determine which hardware component might be at fault. When testing is complete, Apple Diagnostics shows the results, including one or more reference codes. Learn about Apple Diagnostics reference codes. 

Let us know which reference codes you receive.

Finally, let us know what antivirus, VPN, or cleaning software you have installed. 

Jack

If you're looking to speed up performance by nearly 20x for read and 7 x for write an external SSD for the boot drive would be the way to go. A second benefit would be it's easy to create and you can take it with you when you replace the iMac.

The following is the speed test on a bare external SSD using a SATA to USB C adaptor:

I also have a number of bare SSDs in OWC drive docks:

If you're interested in this route I recommend drives from OWC (MacSales.com) as they have proven reliability, excellent customer support and warranties.  Consider one of these depending on your budget and needs: 

OWC Envoy Pro FX Thunderbolt 3 + USB-C Portable NVMe SSD

OWC Envoy Pro SX Rugged Portable NVMe SSD with Thunderbolt/USB4

OWC Envoy Pro Elektron USB-C portable NVMe SSD

Envoy Pro EX with USB-C or USB 3

OWC Envoy Pro SX - up to 2847 MB/s 

For your model contact OWC's customer support and get their recommendation for the SSD model that would best suit your iMac model, work requirements and budget.  They may have additional models other than those I've shown above.

Yossarian203 wrote:

Would I clone the new disk from my current one? I assume this forum could help with that. The info is much appreciated, thanks!

Yes. You would do that with Carbon Copy Cloner .

1 - make sure you have a full and current backup of your drive.

2 - erase the external SSD and format it to ASPF with Disk Utility.

3 - using Carbon Copy Cloner drag the internal drive into the Source bin and the external SSD into the Destination bin:

3 - Control (right) - click on the Destination bin and select Legacy Bootable Backup Assistant from the contextual menu:

4 - then click on Start.

When done select the external SSD as the startup drive in the System/General/Startup Disk settings pane and reboot.

Download and run Etrecheck. Be sure to give it Full Disk access before running.

Copy and paste the results into your reply. 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 paste the report in your reply.

Then we can evaluate the report to see if we can determine the cause of the problem.

Yossarian203 wrote:

So are we thinking it's a hardware issue now? Should I be looking at an external SSD for a boot drive?

Not until you clear the software interferences that can slow storage devices. All that unneeded software (CleanMyMac; MacKeeper (awful!!); VPNs; etc will mask true hardware issues.

A healthy, unencumbered Fusion Drive array should be doing writes in the 500-900MB/sec range and Reads up to 2000MB/sec. Those are NOT slow speeds. Yours are slow.

I've another post that said maybe the cheap-*** HD's they were using may be the problem?

That is more true of the 21.5-inch models that did not have room inside for a larger and more reliable 3.5-inch hard drive.

That is why the EtreCheck report is important. 27-inch models are more likely to have a faster mech hard drive, an even faster Apple hybrid "Fusion" drive, or a screaming fast factory solid-state drive. The drive type will be detailed in the report without giving away any private or security information.

The only cloning apps that work are Carbon Copy Cloner and SuperDuper. I've used CCC many times and it works file with Intel Macs. This post describes how to use it: Click here



There could be a hardware failure but we should check out the software first. If, after removing those apps, the hard drive gets back to near its original speed you won't need any new hardware. If not then we'll discuss that when you report back.