You already know you can upgrade your Mac's RAM yourself and save big money, but how much extra memory do you want? Yesterday I added a gigabyte to my MacBook Pro to top it out at 3GB, and as you would expect, things are a lot faster when using hungry programs like Parallels and Photoshop. After the jump, take a look at some of my unscientific 1GB, 2GB, and 3GB MacBook RAM performance tests.Machine specs: I'm using a 2.16 GHz Intel Core 2 Duo 15-inch MacBook Pro, which has exactly two memory slots. One of my slots has a 1GB stick of Apple RAM. Yesterday I replaced the 1GB stick in the second slot with a 2GB stick and took some notes on performance differences between the three configurations using all of my most memory intensive programs.
The "test": At any given moment I'm running several small utilities on my Mac (Quicksilver, GeekTool, InstantShot, Hazel, Mozy, TextExpander, MagiCal and Twitterific, to be exact.) Those aren't the problem, but add iTunes, Firefox, Photoshop CS—and the grand poomba of memory consumption, Parallels (especially virtualizing Windows Vista)—and you've got a damn slow computer on your hands. Given that list of running processes, here were my results.
I wasn't able to even run all the programs in the test with only 1GB installed. Once iTunes was open, booting Parallels stopped the desktop from being able to redraw itself (my menu bar disappeared, and bits and pieces of it showed up over time). Quicksilver took about 30 seconds to respond to the invocation keyboard shortcut, the spinning beachball of paralysis showed up intermittently. Windows Vista took an unreasonably long time to boot (for a while there, I was pretty sure wouldn't boot at all).
Here's what the System Memory area of the Activity Monitor looked like during all that jazz:
Notice the big slice of red in the pie (that's wired memory usage, data that can't be swapped out to virtual memory), and the high level of paging activity (swapping data from memory onto disk in virtual memory).
Here's more on how to read system memory usage in the Activity Monitor.
2GB—Result: Sometimes choppy
The 2GB upgrade I did myself back when I bought my MacBook carried me a long way until Parallels running Vista became a regular task. While the 2GB starts up Vista ok with all the other programs running (Firefox, iTunes, etc), you're still no stranger to the spinning beachball of paralysis, and sometimes switching between applications can be choppy and slow. At 2GB, I often found myself shutting down apps just to get OS X to be more responsive.
Here's the Activity Monitor state during my 2GB test:
Here you see the Mac ate up that extra gig (at 1.98GB in use in total, it was basically using all the memory it could) and a lot less (but some) paging activity. Also more (but not much) free memory is available here.
3GB— Result: Snappy with plenty of breathing room
My particular model of MacBook Pro can expand to 3GB max. But the Apple Store does not carry 2GB sticks of RAM to fill that second slot, so I had to buy through a third-party retailer (something I would've done anyway, since Apple prices its memory so high). Rumour has it using a 1GB+2GB memory configuration will break the Mac memory's dual channel performance boost and slow things down. I'm still not clear on the deal with dual channel technology (commenters, feel free to enlighten us), but regardless, the extra gig sped things just as you'd expect. With the 3GB memory upgrade, Parallels' Vista boot-up is snappy and doesn't effect any other apps. Makes sense, because with 3GB, OS X is using 2.85GB of memory with a comfortable 160MB free. Check out this memory pie with a nice big blue slice, smaller red one and a big fat goose egg for page out's:
Captain Obvious' Moral of the Story
It's no surprise that upgrading your computer's memory will make it a hell of a lot faster. But I hesitated to upgrade my MacBook to 3GB for some time now, since that 2GB stick will set you back almost 200 bucks and I wasn't sure how much of a performance boost I'd get out of it.
A day into having that extra gig plugged in, though, my only regret is not doing it sooner.