[OnTheKeys]

So here's an interesting little problem.

When I boot my computer, I have about 3.x GB of RAM free via the pie chart in Activity Monitor.

Then I'll load up Cubase, load some virtual instruments into it (maybe about 2GB), close it down but I will still have that RAM usage.

Here's a picture:

http://www.tyler-johnson.net/RAM.jpg

It shows that Cubase is taking up the most space and it's only consuming 126 MB, but it says I have 2.69GB in use.

[OreoCookie]

OS X loads a lot of stuff into the RAM by default so that launch times of apps, for instance, are quicker. Ideally, all of your RAM would be used (you still have 1.3 GB available). What you want to avoid are page-outs (when OS X is forced to use the virtual memory on the harddrive). If you have free RAM, then there will be no page-outs.

[OnTheKeys]

But when I boot up my computer it shows that I have about 3.36 GB Free, but after loading cubase and insruments, then closing the program thus removing the instruments from RAM it still shows lots of RAM usage.

[OreoCookie]

Yes, as I said, it's intended. The next time you launch Cubase, you'll be able to launch it faster.
Nothing is wrong and everything works as expected. You don't have insufficient RAM either, so everything is in the green.

[Spheric Harlot]

The key is the idea that unused RAM is WASTED RAM.

In other words, if you have lots of free RAM, that's a complete waste of resources.

So the OS will just keep all sorts of stuff in the RAM that's not currently needed, just in case you might want to access it again. Net performance gain.

[mduell]

If you quit Cubase, does a large chunk move from Active to Inactive?

OS disk cache is usually categorized as inactive rather than active on other Unix-like OSs.

[OnTheKeys]

Ahhh I see, that makes perfect sense. I thought that this would slow down the computer's performance, but really it's a more efficient way to run things. Thanks guys!