What are redirect chains and why do they slow a website down?
A redirect tells the browser "the page has moved, go here instead". One redirect is normal, for example sending www to non-www or http to https. A redirect chain is when the destination redirects again, and again, and each hop is a full round trip to the server before the real page can even be requested.
Why it matters
On a fast home connection a redirect costs a fraction of a second. On a phone with a weak signal each one can cost half a second or more, so a chain of three can add well over a second before anything appears. Search engines follow the chain too, and each hop leaks a little of the ranking value the original link carried. Google stops following after a handful of hops and treats the page as unreachable.
How chains build up
They are rarely deliberate. A site moves to https, so http redirects to https. Later it drops the www, so www redirects to non-www. Then a plugin adds a trailing slash rule. Each rule is correct on its own, but an old link now bounces through all three before it lands.
How to check
Our check counts the redirects between the address you typed and the page that finally loaded, and shows the final address. You can also see them in any browser's developer tools under the Network tab: each redirect appears as a row with a 301 or 302 status.
How to fix it
Point every old address straight at its final destination, so any request takes at most one hop. Make sure links inside your own site already use the final form: https, with or without www as you have chosen, and with the trailing slash your site uses. If the chain crosses a domain change, the old domain should redirect directly to the matching page on the new one, not to its home page.
Not sure how your own site does on this? Run the free check: it takes about twenty seconds and reports on this and thirty other things.