Use Activity Monitor to find out why your Mac is so busy

Use Activity Monitor to find out why your Mac is so busy
Quick Mac Tip, 06 March 2011

Does your Mac suddenly seem slow? Is it busy all the time doing something, but you don’t know what? Activity Monitor can help you figure out what’s using up all your processor time. Here’s how to check it out.

Activity Monitor shows what is using the processor on your Mac.

Activity Monitor shows what is using the processor on your Mac. The Flash Player in Safari was using 35% of my CPU at the moment the screenshot was made.

Overview of steps

  1. Open Activity Monitor.
  2. Click on the CPU tab.
  3. Show All Processes.
  4. Sort by % CPU with largest number at the top.

Open Activity Monitor

Activity Monitor is in the Utilities folder in the Applications folder. Double click to open it.

A window appears where you can view the status of your Mac across many areas: disk activity, dick usage, system memory, and so on.

Look on the CPU tab

To find out what may be slowing down your Mac click on the CPU tab in the lower half of the window.

Show All Processes

In the Toolbar at the top of the window make sure that All Processes is selected from the Processes pop-up menu.

Sort by % CPU

Click on the header of the % CPU column until the arrow beside the words points downwards. That sorts the column so the biggest number is at the top of the list.

The list should be constantly changing as different tasks use more or less of the processor.

The Flash Player at the top of the list in my screenshot sometimes used as little as 2% of the processor and sometimes as much as 70%.

Sometimes it will be obvious what’s using the processor, as in my Flash Player example. Sometimes though, you’ll only see a mysterious name, such as usbmuxd. In that case you’ll have to try a Google search for the name of the process.

Take action

How you might respond to the information about what’s using the processor depends on what you see. But at least now you’ll have a starting place.

In my case, I found I’d left a Flickr slideshow running in Safari, even though I was no longer interested in it. All I had to do was close that tab in Safari, or quit and open up Safari again.

A friend who had a problem that sparked this Tip realised he’d set Spotlight to run on his machine. Its initial indexing process was slowing his machine down in an annoying way. He simply needed to stop Spotlight while he was working and leave it to create its index overnight while he was sleeping.

You may find that a particular application always causes problems for you, or that you need to change your work habits, or perhaps add more RAM.

Or if your machine doesn’t seem at all slow you won’t need to do anything. Take a look at Activity Monitor now, just to become familiar with it. And if your Mac ever seems unusually slow use Activity Monitor to check up on what it’s doing.

What’s your experience with the Activity Monitor? Tell us in the Comments. Could you write a guest MacTip? If so, contact me.

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