Take Control Of Your Mac’s Memory Usage

Mac OS X is a slick, powerful operating system, but there’s a cost to all that gloss. Most users don’t ever bother to check, but many of the apps they use every day are notorious RAM-gobblers, eating up huge amounts of system memory and making even brand new Macs feel like they’re running slowly. Here’s a look at why you should keep an eye on your Mac’s memory usage, how to monitor it, and which apps are the worst offenders when it comes to memory drain.

Why Your Should Keep Your Eye on Memory

Your Mac’s memory, or RAM, is what allows data that’s normally stored on the hard drive to be used by the processor, like apps. Your computer can access data stored in your RAM significantly faster than it can read data on traditional hard drives, so when your RAM fills up with megabytes of memory dedicated to RAM hogs, opening and running apps can take a very long time.

The average Mac user will have between 2GB and 3GB of system memory at their disposal. Newer Macs are packing 4GB a bit more often, but it’s not quite the norm yet. So, say you’ve got a Mac that’s a couple of years old and has 2GB of RAM. When you turn on your computer, the operating system itself (along with a couple of small apps that run at start-up) will use about 650MB just to run the system. After a few hours of steady use, the base system can use up to 1GB without any other apps open, depending on how much work the computer was doing during those hours.

That doesn’t leave you with very much. In fact, it leaves you with just 1GB of untouched RAM available for running apps. You can run more than that would allow, but that’s when things start slowing down — because your Mac will start to swap data from your super-fast RAM to your super-slow hard drive as it starts to push apps you aren’t using to into the background. Having more RAM won’t make a single app run faster, but it will make a whole system running several apps run faster.

Check Your Memory Usage

In order to get a handle on your Mac’s memory, you need to check to see what’s using it in the first place. Two solid options for doing so include Activity Monitor (which comes with your Mac as a system utility at /Applications/Utilities/Activity Monitor.app), and iStat Menus (a third-party app that displays memory use in your menu bar).

Activity Monitor – OS X’s Activity Monitor is a full-featured system monitor, and it’s more or less the same tool you’ll find preinstalled in Windows and Linux. It will show you everything that’s currently running on your computer, but it only runs when opened. Because it monitors so much, in such detail, it actually needs a decent amount of attention from your processor to run, so it isn’t really ideal to leave it running all the time. If you’re not sure how to read all the information presented in Activity Monitor, just pay attention to the column labelled Real Mem. If you click on that label, all the items in the list will be ordered by how much memory they’re consuming—look for bigger numbers (in MB, not KB).

iStat Menus – iStat Menus is a set of tiny system monitors for your Mac’s menu bar that costs $US16 after a short trial period. iStat runs all the time, and only uses about 3.5MB of memory itself to do it. Any time you’re able to see your Mac’s top menu bar, iStat will show you how much memory you’re using (and plenty of other info, if you tell it to). For the memory monitor, iStat will show you how much RAM is used, and how much RAM is still available. If you click on the monitor, it will show a drop-down info pane that lists the top five memory-eating apps or processes at any given point in time.

Apps that Eat Your Memory

Every app uses memory, but there are some that use disproportionate amounts. That doesn’t necessarily mean they’re bad in any way, but it does mean you might not want them running all the time if you aren’t using them. These are some of the worst:

• Twitter Apps – Nearly all Twitter apps for Mac use more memory than most would think possible. The full version of TweetDeck (Adobe AIR) is by far the worst when it comes to memory use, routinely eating over 200MB, but it also has more functionality than most Twitter apps — so it’s usually forgiven that flaw. Even so, if you don’t need a huge social toolbox like TweetDeck — lighter apps are available. Some smaller apps that showcase their “minimalism” tend to use upwards of 60-90MB, and that’s just as unacceptable if you don’t have gobs of RAM to spare. Not all Twitter apps are memory hogs, though; Itsy, Yorufukurou and Twitter’s official app are three examples that tend to do a bit better than most.
• Music Players – Many users like to have iTunes running all the time, in case they feel like listening to music on the fly. When it’s first opened, iTunes doesn’t use much RAM (usually around 60MB), but after some time that number can grow, especially if longer songs are playlisted. It’s not the worst offender, but if there’s no reason to have it open then you might want to quit the app. Most other music players use up about the same, if not just slightly less RAM than iTunes, so the same goes for them.
• Browsers (especially Chrome) – Browsers are expected to use a decent amount of memory since they’ve grown so large over the years, but one stands out as an absolute beast: Chrome. Because of the way that Chrome works, multiple sub-processes (called Workers) are run as you use it. It doesn’t take very long for there to be a dozen (or more) of these Chrome Workers, and each one usually uses about 20MB of RAM. That’s not all, though. Chrome also spawns other, more specialised worker processes called Renderers, and those can use anywhere from 90MB to 200MB or more, each. The longer you use a tab in Chrome, the more RAM it will consume, so try not to keep any one tab open too long.
• Desktop Bling (like Geektool or Bowtie) – Plenty of Mac owners are using tools like Bowtie and Geektool to customise their desktops, but they rarely check to see how much memory those “simple” tools consume. Bowtie is a small app that displays the currently running track from iTunes, and while it’s extremely simple in looks, it uses an average of 90MB just to run. That’s quite a commitment just to see a song title on your desktop. Geektool, on the other hand, is a tool that can display anything on the desktop. It’s a truly amazing app, and it’s closest Windows-side sibling is probably Rainmeter. The problem with Geektool, is that it has a tendency to gobble up astronomical amounts of memory for seemingly no reason. Just using it to run a small text calendar and, ironically, a system load monitor, can lead to RAM usage of up to 750MB (or more).
• Dashboard Widgets – If you use a small amount of Dashboard widgets, say six or less of those that came preinstalled, then they’re not much of an issue in terms of RAM usage. If you use many widgets, on the other hand, then you could be spending 60-80MB on them. It’s entirely possible to dump up to 200MB of RAM into the Dashboard alone, and most of us hardly use it.

Next time your Mac is feeling slow, take a look at what’s running. Does it need to be? Is there another option that uses less RAM? These are all things that need to be considered more often, because apps are only getting bigger.