More apps are offering an option (in preferences) to reduce the amount of memory they use when minimized to tray. Password Safe uses the same amount of memory whether the main UI is open, or sitting locked in tray, AFAIK. There's no point in that - it's usually not monitoring or carrying out operations while it's minimized.
Prgms like Screenshot Captor http://www.donationcoder.com/forum/index.php?board=34.0
seem to reduce memory use while minimized to tray to almost nothing, while having very little effect on time to restore / maximize the main window, containing a large graphic.
If all prgms sitting idle in the tray would do this, there'd be a lot of extra free RAM - esp. for machines / laptops w/ lower total RAM.