The only header that I can think of that might slow down a site is Content-Secur...

		tomschlick on May 22, 2017 \| parent \| context \| favorite \| on: HTTPS on Stack Overflow: The End of a Long Road The only header that I can think of that might slow down a site is Content-Security-Policy. Even that is negligible as long as you don't have 1000 entries.