Claude Cowork is unusably slow on my M1 MacBook Pro. I wonder if Codex is any better; a quick search indicates that it is also an electron app
Claude Code, on the other hand, has no such issues, if you've done some setup to allow all commands by default (perhaps then setting "ask" for rm, etc.).
Their naming is not very clear. The codex desktop app is somewhat of a frontend for the codex cli.
By the look and feel of it I would guess it is written with Electron.
I just updated Codex and looked inside the macOS app package. It is most definitely still an Electron app.