fxcleared after 14 days idleyou ↔ server — · server 0.8 msOne server, in Los Angeles. That is the whole explanation.
Your round trip — keystroke to confirmed value — is not yet measured. The server’s own share of it, its running median for commands that change a sheet, is 0.8 ms. The rest is network distance between you and Los Angeles.
Closing that gap is a deployment decision — more origins, or one nearer you — not an architectural one. Nothing in the application is doing that work.