OS X: Three Common Causes of Slowdowns

If your Mac is as slow as molasses or you’re seeing the dreaded spinning beach ball of death a lot, it’s time to do some sleuthing.

Of course, slowness can often be attributed to age—just because your 2010 MacBook Air can run Yosemite doesn’t mean that’s gonna work out amazingly well for you—but even so, it’s best to figure out what’s going on. To that end, let’s start troubleshooting the three most common causes of sad, slow Macs!

1. You could be running out of RAM. A lot of people misunderstand what RAM is and how it works. I’ll hear things like “I empty my trash and clean off my desktop! I shouldn’t be out of RAM!” For confused folks, I like to use an analogy. Your Mac’s storage (your hard drive or SSD) is like a filing cabinet; it’s where you keep all of your documents. The RAM (memory) is akin to the surface of your desk. You take stuff out of your filing cabinet and plop it on your desk for quick access, just like your Mac uses RAM to get to items you’re using frequently. If you fill up the surface of your desk, you’ve gotta start putting folders back into your filing cabinet to be able to pull out more, and this is exactly what your computer does, as well.

When too many programs, documents, browser tabs, and so on are running at once, the Mac starts swapping data out to your storage drive to make up for not having enough memory, which is way slow. If you can imagine having to swap a folder back into your virtual filing cabinet every time you want to look at a new one, you’ll get an idea of what your Mac is probably trying to do when it’s giving you that sad little beachball.

You can check to see if that’s indeed the problem by first opening a program called Activity Monitor—it’s within Applications> Utilities.

If you then click on the “Memory” tab, you’ll get a handy-dandy guide at the bottom for how much you’re using.

Ruh roh.

The important things to note are “Memory Pressure” (which’ll turn yellow or red if your Mac thinks your RAM usage is outta control) and “Swap Used.” If you see gigabytes of swap (remember the desk/filing cabinet analogy?), you could definitely benefit from more RAM. Keep in mind, though, that “Swap Used” resets to 0 when you reboot, so you might have to wait a day or two after that happens to get an accurate idea of how much your Mac is struggling.

Whew! So what can you do about running out of RAM? Well, you could try quitting programs when you’re not using them and making sure that you aren’t opening thousands of browser tabs at once. Use fewer of your Mac’s resources, and you’ll have more available when needed.

Alternatively, you could buy additional RAM and install it if your Mac supports doing so. See if it does by clicking on the Apple Menu in the upper-left corner of your screen, choosing “About This Mac,” and then clicking on the “Memory” tab. 

See that “Memory Upgrade Instructions” link? Click that, and you’ll be taken to an Apple support article with step-by-step guidelines for RAM installation on your model, if available. If your Mac can’t be upgraded, however, the “Memory” tab may not show up at all, or you may not see the “Memory Upgrade Instructions” option (or your Mac won’t be listed on any of Apple’s RAM upgrade pages when you search).

Once you’ve decided that you’re gonna upgrade your RAM, pop on over to Crucial’s website, which is where I recommend purchasing it. The great thing about that site is that you can download and run their System Scanner, which will tell you how much RAM you have, how much you can upgrade to, and what kind you’ll need. They make it easy as pie.

2. You’re running out of drive space. Oh crap. If you get too low on free space on your disk, performance will suffer, and if it gets bad enough, you may not be able to do much of anything on your machine. Keep an eye on this within the Apple Menu > About This Mac option mentioned above, under the “Storage” tab:

If you’ve got less than 10GB remaining, take action! Emptying your trash, cleaning out your Downloads folder, and deleting movies or TV shows from iTunes (since you can redownload anything you purchased from Apple) are good places to start.

3. Something’s wrong with your disk. Let’s hope this isn’t the case, as having to take your Mac in for a hardware repair is never awesome. For a preliminary check, open Applications > Utilities > Disk Utility, pick your startup disk (usually “Macintosh HD”) from the left-hand list, select the “First Aid” tab, and click on “Verify Disk.” 

You’ll get a warning that your Mac will act oddly while the test is running, and then it’ll check for problems with the disk. You’re looking for all green text here, so if anything shows up in red, you’ll need to take further action.

If you do see red text indicating that there’s a problem, there are a few things to attempt. First, you could boot into the Recovery System, where you could repair the disk if necessary; next, try running Apple Diagnostics, which’ll check for hardware issues and help you understand your support options; or if nothing seems to be working, you could just go ahead and visit the Genius Bar. If you use the “Repair Disk” feature within the Recovery System and it reports that it has fixed the problem, you’re probably OK, but be aware that failing drives can be notoriously difficult to diagnose.

If you suspect that’s the issue—for example, if you have constant spinning beach balls and crashes, but you’re not running out of RAM or disk space—BE SURE to back up your computer. Or just, you know, back up your computer every day anyway. Why? Because you don’t want to be one of those cautionary tales that I get to write about.

I’d estimate that about 90 percent of the slowdowns I see are caused by lack of adequate RAM, so even if your Mac has become crawlingly slow, don’t stress too much before you troubleshoot the issue. And as always, it’s good to try rebooting your computer before you freak out. If you think your drive is failing and you don’t have any backups of your data, though, you then have my permission to freak out. I’m stressing a little just sitting here imagining that scenario. Yuck.