Note that hackernews is notoriously anti “marketing speech”. I don’t think there’s anything bad with elaborating but lightweight/snappy/slim is pretty much what’s important, given that there’s so much slow bloatware out there. Not all users are technical, and eg throwing out benchmarks on the front page would be complete mumbo jumbo to many users.

That said, I also think the best way to communicate the intended vibe is also through screenshots (which you already have) and design. Looks awesome.

In that case I'd go straight to "responsive" or "fast" or something. The vast bulk of users literally don't understand what we mean by lightweight; ask around as to which is larger, a kilobyte or a gigabyte, with your non-technical friends and I bet you find even the ones who get it right do a lot more fumbling than you expect.

Yes, I like responsive too, although it’s borderline industry jargon. I still think snappy is perhaps a bit more down to earth but I don’t know how common it is outside of American English, which could be a problem with an international audience.. words are hard.

I think the important thing to get across isn’t binary size or even RAM usage per se, but rather that it’s the opposite of bloated. Regular non-techies are tortured every day with really slow and unnecessarily networked applications. There was a thread like a month ago about the 400+ MB LinkedIn iPhone app.

Lightweight is a great adjective when comparing with existing "heavyweight" software - most people would understand what it means if you say "Numbers is a lightweight Excel-like spreadsheet"; "Zoom is a lightweight Go-to-meeting".

As a stand-alone adjective it's not as useful.