Regarding RAM consumption. I'm on a Windows box right now. The Windows Desktop Manager takes ~75MB RAM, but my Firefox process (with most tabs suspended) takes >2GB RAM. I run into the same on my Linux and BSD machines at home.
I run i3 and the XFCE settings daemon for convenience. Sure, I could optimize more, but it's really not the area where I'll see a lot of benefit. My best optimization for standard users is an automatic tab suspender.
When casual users insist on needing 16 GB of RAM to surf the web, watch videos and chat it makes me cringe.