After I set always use https, my score on Pingdom downgraded from A to B, because there’s a redirect (from http to https). I also install SSL Fixer plugin on my WordPress site. How to implement always use https without downgrade my score on Pingdom?
It’s normal for a redirect to lower your Pingdom score. Since you’re telling Pingdom to test your HTTP, it’s getting a redirect. Have it test your HTTPS url instead.
On a side note, if you have your site redirect to www or non-www, the same thing will happen if you tell Pingdom to check the opposite URL.