使用影响pagespeed得分的.htaccess将非www重定向到www

I'm redirecting my web page from non-ww to www using this htaccess

RewriteCond %{HTTP_HOST} ^mywebsite.com [NC]
RewriteRule ^(.*)$ http://www.mywebsite.com/$1 [L,R=301]

but it degrades my pagespeed point for about 6 points for Avoid landing page redirects reason.

Any idea how to fix this?

That is because this redirect is being triggered like so

request (mywebsite.com) -> Response (redirect to www.) -> request (www.mywebsite.com) -> response

If you directly test www.mywebsite.com those two redirect steps will be avoided and your page speed score will increase.