My dad's macbook pro mid-2012 is really slow - even after putting 16gb of RAM in it.

Your dad has a perfect excuse to get an SSD now. I wouldn't worry too much about the brand as long as it's a pretty recent model. They all perform about the same speed because of the limitations of the SATA III interface.

And while your at it it might be worth replacing the SATA connector ribbon "cable". There are several compatible aftermarket parts out there. I didn't, but others recommend doing it as a preventative measure since SSDs seem to be more sensitive to a bad connector.

Stefanoeast wrote:

Yes. Is that bad? I mean he hasn't been rough with it. But I suppose you're suggesting that's the issue? But Disk utility didn't find any problems when I ran first aid. Or is that pretty superficial?

Thanks for your help.

Yes that is the suggestion, the HD is 6 yrs old.

Failing HD issues are extremely hard to diagnosis, it can be SMART verified, no errors in Disk Utility, pass all AHT etc.; and you can work through every suggestion on Kappy post above, and literally spend months trying to figure it out, until a catastrophic failure.

The go-to-way to test is to simply boot off an external boot clone of your macOS. This will bypass both the HD and the internal SATA cable. How to create a boot clone.

From OWC you can buy a kit (SSD, enclosure, tools). Search Results for DIY KIT OWC Express at MacSales.com

Your 2012 is USB 3 compatible, and SATA III can run the 6G SSD (2.5'' form factor.) If you upgrade HD/SSD definitely install a new SATA cable at the same time for a nominal expense.

Stefanoeast wrote:

Yes. Is that bad? I mean he hasn't been rough with it. But I suppose you're suggesting that's the issue? But Disk utility didn't find any problems when I ran first aid. Or is that pretty superficial?

Thanks for your help.

Hard drives are mechanical and inherently wear out. Disk Utility really only detects gross errors such as a corrupted volume. The drive could be marginal. Maybe going to lots of error correction.

Given it took over 27 minutes to run etrecheck, a task that should complete in about 5 minutes, I suspect your hard drive is failing.

Stefanoeast wrote:

So as I said, it's a mid-2012 Macbook Pro. 2.5Ghz Intel Core i5. 16GB 1600 MHz DDR3. 500gb SATA HD with 344GB available.

Let me ask you this— is this the original OEM HD that shipped with the Mac ?

Ways to help make a slow Mac faster

1. 17 Reasons Why Your Mac Runs Slower Than it Should
2. Slow Mac Performance? This Article Solves It!
3. Fix slow start-ups in OS X | MacFixIt - CNET Reviews
4. How to fix slow shutdown and startup times. | MacTip.net
5. 6 Easy Tips to Speed Up OS X Yosemite on Your Mac
6. OS X El Capitan- If your Mac runs slowly
7. Visit The XLab FAQs and read the FAQ on Performance
8. Tips to Fix Issues that affect Mac Performance
9. Avoid using any third-party cleanup software. Usually, this software does more bad than good. You don't need it. All computers become slower over time even under normal use. Experienced users erase the hard drive and do a clean install from scratch from time to time; or whenever installing a major OS upgrade. Doing so means you must maintain regular and multiple backups.
10. If you have enabled iCloud Disk and are storing your Documents and Data in iCloud, then consider turning that off and signing out of iCloud. It can slow down the computer considerably. Please see the following from the user, fotomac: "The solution was to SIGN OUT of iCloud and my problem STOPPED! NO MORE SPINNING BEACHBALL! My computer's speed increased to what it should be and all my Apps now work!"
11. Add more RAM or cut back on the number of concurrently running applications and utilities. Remove unnecessary anti-malware software and any software that promises to clean your Mac. Check for runaway processes: Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity. Also, visit The XLab FAQs and read the FAQ on dealing with The Spinning Beach Ball of Death.
12. The Ultimate Fix: Backup everything, erase the drive, reinstall OS X, and restore your data from the backup. Reinstall third-party software from original media/scratch.

A Troubleshooting Procedure that may Fix Problems with macOS El Capitan or Later

You should try each, one at a time, then test to see if the problem is fixed before going on to the next.

Be sure to backup your files before proceeding if possible.

1. Shutdown the computer, wait 30 seconds, restart the computer.
2. Disconnect all third-party peripherals.
3. Resetting your Mac’s PRAM and NVRAM
4. Reset the System Management Controller (SMC)
5. Reset your Startup Disk and Sound preferences.
6. Start the computer in Safe Mode. Test in safe mode to see if the problem persists, then restart normally.
7. Use Apple Hardware Test to see if there is any hardware malfunction.
8. Repair the disk by booting from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volume entry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and return to the Utility Menu. Restart the computer from the Apple Menu.
9. Repair permissions on the Home folder: Resolve issues caused by changing the permissions of items in your home folder.
10. Create a New User Account Open Users & Groups preferences. Click on the lock icon and enter your Admin password when prompted. On the left under Current User click on the Add [+] button under Login Options. Setup a new Admin user account. Upon completion log out of your current account then log into the new account. If your problems cease, then consider switching to the new account and transferring your files to it - Transferring files from one User Account to another.
11. Download and install the OS X El Capitan 10.11.6 Combo Update or 10.12.6 Combo Update or Download macOS High Sierra 10.13.4 Combo Update as needed.
12. Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
13. Erase and Install OS X Restart the computer. Immediately after the chime hold down the Command and R keys until the Apple logo appears. When the Utility Menu appears:

1. Select Disk Utility from the Utility Menu and click on Continue button.
2. When Disk Utility loads select the drive (out-dented entry) from the Device list.
3. Click on the Erase icon in Disk Utility's toolbar. A panel will drop down.
4. Set the Format type to APFS (for SSDs only) or Mac OS Extended (Journaled.)
5. Click on the Apply button, then wait for the Done button to activate and click on it.
6. Quit Disk Utility and return to the Utility Menu.
7. Select Reinstall OS X and click on the Continue button.

14. If none of the above helps then see How to Downgrade macOS High Sierra and macOS Reversion- How to Downgrade from High Sierra.

15. If you get here without success then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.