While most users with a modern MacBook Pro or iMac will never bother with looking at memory usage, simply because there is enough RAM installed to keep most apps running simultaneously without an issue, but for power users such as myself, even the 4 GB that my MacBook Pro comes with is sometimes not enough. I sometimes have more than 10 apps running simultaneously, and the biggest memory hoarders are Firefox, Eclipse and Vuze. A time comes when there is simply no more memory left for new apps, and thus the whole system starts to slow down (especially app-switching) since new application data is now loaded directly from the disk rather than the RAM.
FreeMemory is a freeware tool for Mac OS X that claims to help you free some of your precious memory to make space for more apps. Its a utility that acts both as a monitor as well as optimizer, and sits in your status bar, therefore does not have any UI of its own. In its idle state, it will indicate the amount of memory that is free. For example, right now its indicating that 1.23 GB of memory on my system is free.
You can click on the status bar icon to reveal a drop down, where you can either view the current memory usage details, or perform the ‘Free Memory’ operation.
Here’s a quick summary of what the 4 types of memory indicated in the above screenshot refer to (quoted from Apple’s website):
This is RAM that’s not being used.
Information in this memory can’t be moved to the hard disk, so it must stay in RAM. The amount of Wired memory depends on the applications you are using.
This information is currently in memory, and has been recently used.
This information in memory is not actively being used, but was recently used. For example, if you’ve been using Mail and then quit it, the RAM that Mail was using is marked as Inactive memory. This Inactive memory is available for use by another application, just like Free memory. However, if you open Mail before its Inactive memory is used by a different application, Mail will open quicker because its Inactive memory is converted to Active memory, instead of loading Mail from the slower hard disk.
When I actually performed the ‘Free Memory’ operation, I noticed that most of the memory that the program was able to free was from the ‘Inactive Memory’ group. Now if you’ve read the description of the ‘Inactive Memory’ above, then its easy to realize that freeing up that memory is actually bad for performance, since the memory that was held by those applications will be loaded again from disk the next time they are launched.
Effectively, FreeMemory is just putting a statistic in front of your eyes that seems to be effective, but is actually not optimal for performance at all. Nevertheless, it does free a small amount of Wired and Active memory as well, which can be useful in certain situations.