We help IT Professionals succeed at work.
Troubleshooting Question

My MacBook Catalina has been Dog Slow for weeks

Last Modified: 2020-08-14
I need help on a very slow MacBook (Catalina).

I need help first checking:
- Is the disk full?
- Is there some process running?
- Is there a virus? (I just ran Avast Premium Security where 167,247 files were scanned and was told "You're all clear")
- What about my browser/browser plug-ins/router settings that may influence performance

This part scares me, so please help me do an investigation and be sure these are destructive tests. If I lost my Internet connection, I would be in trouble. Also, a change to the router could stop me from doing my day job, since I also work from home.

Watch Question

curiouswebsterSoftware Engineer


I did just run the following:

cat /etc/resolv.conf

and got:
# macOS Notice
# This file is not consulted for DNS hostname resolution, address
# resolution, or the DNS query routing mechanism used by most
# processes on this system.
# To view the DNS configuration used by this system, use:
#   scutil --dns
#   dns-sd(1), scutil(8)
# This file is automatically generated.
search fios-router.home
Distinguished Expert 2019
This problem has been solved!
(Unlock this solution with a 7-day Free Trial)

Click on the Apple Menu
Click on About This Mac
What year is you Mac.  How much Memory does it have.  If you have 8 GB or less, you may be swapping to disk, slowing everything down.  You really need a new computer if you have any of the non-cat OS X (10.9 and newer.)  8 GB was really last useful in Mountain Lion, unless all you do is surf the web with 2-3 tabs.  (considering how bloated Chrome is)

Click on Storage
Wait until the bar shows up.  Is it full?

Reset your SMC
    Turn off the MacBook
    Plug in the power
    Press and hold the left shift control  option keys then press and hold the power button

Reset your PRAM
    Turn on the laptop.
    Press and hold the command option p r keys until you hear 3 chimes (older systems) or until you see the screen flicker on, then off 3 times.
   Release the keys

If it's still slow
try booting into recovery mode by holding command r at startup
Select Reinstall OS X and reinstall.
You should make sure you have a backup to be safe, but this should not erase your data.  You will have to erase the disk first with disk utility if you want to do a clean install.  It should take about 30 minutes on SSD and 60 minutes on HD, assuming that your internet connection is working correctly.  This will reinstall all the OS X system files and make them new again, in case any of the files were corrupt.

How much

Do you have a mechanical drive, a fusiondrive or a solid state drive?
If your drive is going bad you'll see noticeable performance issues. And if the drive is more than, say 90% full (not that you should let it get that full) then you'll also have performance issues not to mention it kills the life of your SSD.
David FavorFractional CTO
Distinguished Expert 2019

You missed the more important test.

Run Applications -> Utilities -> Terminal -> top

See if your machine is swapping or some program is spinning your CPU.

Running top is always your best first step.

If you're unsure how to understand your top output, let top run for a few iterations to show CPU hogs, then attach a screen shot of your Terminal window.
curiouswebsterSoftware Engineer


I will run top shortly.

> Uninstall Avast Premium Security is your only solution as it is NOT compatible with Catalina.

Do I simply select them in Applications and Move to Trash?

I have Avast Secureline VPN AND Avast Security

> Click on Storage
Wait until the bar shows up.  Is it full?

Click on Storage Where?


Most RealTime Antivirus software need an uninstaller.  Avast has one as well: https://support.avast.com/en-ww/article/Uninstall-Mac-Security/

Click on Storage in the About this Mac window.

Activity Monitor.app is much easier than running top in the command line and provides other information tabs too.

curiouswebsterSoftware Engineer


I am sure those were all great answers. But, removing Avast solved the problem. Thanks.

Gain unlimited access to on-demand training courses with an Experts Exchange subscription.

Get Access
Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Empower Your Career
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE

Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

  • Troubleshooting
  • Research
  • Professional Opinions