It doesn't need to be. It's a bookmarklet. You click it when there's a sticky header. If it takes 200ms to run, that's not a problem. If it were a browser ext

It doesn't need to be. It's a bookmarklet. You click it when there's a sticky header. If it takes 200ms to run, that's not a problem. If it were a browser extension running on every page, sure, that's a disaster.