skeletonbow: Steam is consuming 400MB across it's multiple processes on my system right now, are you sure you added up all of the Steam processes?
Fenixp: Yeah, unless Steam has processes which contain neither Steam nor Valve in their name / description. Didn't really look beyond that. My Steam is currently idling in the background - isn't yours downloading/updating something?
My steam is sitting in my systray doing nothing, the memory usage (Working Set) is the 4th column of numbers in the screenshot. Just mentally adding up a ballpark, the 5 Steam processes add up to about 570MB give or take at the moment. Galaxy is using only about 280MB currently.
The numbers for both are trivial noise as far as I'm concerned though. Most of the memory used by any web browser period whether it is a regular browser like Firefox, Chrome, IE, Safari, Opera etc., or it is a modern gaming client like GOG Galaxy, Steam, Origin, Uplay - is mostly post-processed web content such as decompressed JPG/PNG and other images, video data and other content as well as javascript application data etc. Even when you leave a web page for another one whether it is in Firefox, Chrome, Steam or presumably Galaxy, it will cache the prior data because web browsers do that - and it uses up some memory.
The amount of memory reserved for caching data will vary depending on the amount of RAM in the system and the applications built in defaults etc. So some people may see their app using a lot more RAM and others seeing it use a lot less RAM. Someone for example might see my Steam using 570 RAM and think "Oh crap, I'm not using that, that's mega bloated!" But it isn't really. I have 32GB of RAM and it is most likely scaling up the size of the buffers it uses to cache web page content just like any web browser would in order to optimize the speed of displaying the content instead of having to reload it over the network more often. On a much lower RAM machine, it will likely cache far less data and use far less memory.
Web pages today offer rich content that consumes a lot more resources than it did say 15+ years ago, but our computers have evolved in that time frame to handle that too, so content providers take advantage of it to provide a richer experience for us. Personally I like that experience whether it is in a traditional browser, a gaming client or both. Anything that improves my overall user experience, adds convenience or other value is something I tend to like, and I don't mind it using reasonable CPU/RAM resources to provide the experience as long as the usage is reasonable for what it's doing. As a developer, I think a modern browser or gaming client using 200-500MB of RAM to provide a rich web based UI with graphics and video, javascript etc. and a nice user interface is pretty reasonable personally but then I have a modern reasonable computer too. On a 12 year old PC it would be a slugfest. :)