Is it true that if you put a trailing slash at the end of the permalink, it would load faster for a single or a multisite WordPress post? Also, is this better for SEO?
If the permalink is to a file with an extension, no trailing slash is needed.
If the permalink is to a directory, a trailing slash is preferred. Otherwise, the server will respond with a redirect and the browser will have to add the trailing slash and make a second request automatically.
http://www.domain.com/adirectory/ is served immediately by the server http://www.domain.com/adirectory browser must make a second request with trailing slash