Why Doesn't Photoshop relase RAM?
 

I had recently been working on a few images, saved them all and closed them, but had left photoshop (PS2) open. Earlier I'd had task manager open to exit a "non-responding" programme and when I switched to TM I noticed that although PS CPU usage was 0, the memory usage was 616Mb (I have 1Gb RAM). Closing PS and reopening then showed again CPU useage 0 but RAM uage only 74Mb

Opening a 130Mb psd file took RAM usage up to ~450Mb with free memory showing ~250Mb.

Opening a second psd ~110 mb took RAM uage to 616Mb with free memory down to 75Mb.

Opeinh a 3rd psd left RAM used by PS and free memory unchanged therefore I guess that PS must be using hard drives as virtual memory.

Closing down all the images, with PS idle but still showing 616Mb used.

Do I need to change a setting somewhere to get unused memory freed up? Interestingly images don't open any faster when PS is freshly opened and only using 75Mb RAM or when its been working and is using 600+Mb RAM

Adobe products tend to grab all the memory they can and are reluctant to give it up.

it wont work slower as its just replacing the "parts" of the ram previously used with fresh data whilst reserving "space" on your ram for quick access. You should find that opening another memory hungry programme will use this reserved space and the quoted usage by PS will drop . your right about PS using your virtual memory - it will do a lot - so regular defrags of your HDD is neccassary. i hope I explained this without sounding more confusing

There is a long answer and a short answer. The long answer involves a lot of technical detail, much of which I am not up the speed on, and is very difficult to understand.

The short answer is very short. Unfortunately, I can't repeat it here because this is a family environment.

There is also a medium-length answer, which is probably the most useful one of all. It is because Photoshop is a vast, poorly designed monolithic application that gets far too little attention from its owners because there is no point in fixing up its many faults. It's cheaper and easier to simply buy out and shut down any competing product the moment it even remotely threatens to disrupt Photoshop's comfortable and very lucrative monopoly. For a while there, it looked as though Paint Shop Pro was going to threaten the Photoshop monopoly. Luckily (for Adobe) Corel bought the company, saving Adobe a lot of money, because PSP can now safely be left to self-destruct in the hands of the same bugfest experts who destroyed Word Perfect in just a few short years.