Yesterday I picked up 8GB (4GBx2) RAM for my 2009 17-inch MacBook Pro (MBP). I decided I should upgrade from 4GB for one reason. I read an article several days ago that explained when to upgrade your RAM. When? When your system is using more than its physical memory and is tapping into virtual memory, which uses the hard disk. Compared to RAM hard disks, including SSDs, are slow.

My MBP wasn’t slow as far as I can tell. After replacing the hard disk-based startup disk with a SSD back in 2011, my MBP felt brand new, faster than brand new. Apps launched so much faster than before I couldn’t tell my system wasn’t running at close to 100% of its potential.

After reading the when to upgrade my RAM article, I launched Activity Monitor and noticed my system was tapping into virtual memory quite a bit. I decided I needed to upgrade my RAM.

Other World Computing is where I get most of my Mac stuff. The 8GB RAM upgrade was US$100+. I thought, “For a sub-$1000 machine $100 to upgrade 4GB to 8GB RAM is a lot.” So I looked for options on Craigslist, and fortunately someone was selling a like-new pulled set (4GBx2) of OWC’s for $40. I picked it up yesterday and upgraded my RAM.

Activity Monitor tells me my system is using a little over 5GB of RAM, and tapping into 0 bytes of swap. My MBP is snappier all around and I’m quite satisfied. Well worth the $40 investment.

My 2009 MBP is now maxed out. Well, I can upgrade the SSD to a faster and larger one, but that’s it. I’m hoping OS X 10.10 will require the same or less hardware resources — I know, probably not — because I’d like to keep using my MBP as my main computer for many more years.