When you see “Secure” and a green padlock plus (HTTPS) next to a sites URL it basically means that all the data that goes between you and the site (and vice versa) is encrypted. So nobody can steal data you’re entering on the site – or that it’s sending you. However if you aren’t entering data or the site isn’t sending you any (or showing personal data about you) it isn’t necessary. And encrypting data does slightly slow sites down.
So, in my site only the LOG IN, CONTACT ME and ADMIN pages are secure pages. Especially as the ‘Chrome’ browser wouldn’t let anyone log in to an unsecured login page. Doh! No need for any of the others to be so though. Let me know if you disagree?