On my GNU / Debian testing 64-bit, with 10 tabs opened it consumed 31 MiB of RAM and my CPU pushed itself to reach 0.75% at its busiest processing during typing.
Right now, I'm editing all the files in a 3kLOC project in neovim, doing completion with an LSP host, in 14.8MB. Keep it going for a few days and you might rack up 40MB. People can keep creating lightweight editors all they like, but you really need to bring more to the table than that when vim already exists.