Many DE have received substantial improvements over the last couple of years. It sounds like you’re really looking for something lightweight, more than you are something that is fully featured. I don’t have much experience with the lightweight Linux DE, because when I need performance I just use command line like you do. I’m sure if you did some searching, you could find a really snappy DE, but it doesn’t sound very important for your use case. Definitely do check out some of the full-featured desktops though if you ever decide to use Linux as a primary PC. Several of them are really slick now.