Would adding more RAM to your Mac increase its performance, or would It be a waste of money. Head over to OSxDaily to find out. They have a great article on how to tell if your Mac needs RAM or not. You can read it here
Here a post from the Apple forums that’s a perfect example of when your Mac needs more RAM.
It a nutshell, the Page Outs (see below) value signifies the amount of memory your Mac is drawing from the hard drive. Here’s a screen shot I took today of Activity Monitor.
Obviously the Page Outs on my Mac is quite large. I will be shopping for 4×2 sticks of RAM soon. If you’re not sure what kind of RAM your Mac takes, Crucial has a scanner utility that shows the correct memory to buy.