This is just a tiny "issue", but I thought I would mention it here.
Sometimes when I start on the HTTPS (secure) version of PrimeGrid, https://www.primegrid.com/, after clicking around for a long time, I realize that I am on the non-secure (HTTP) version of the site. I think it would be more professional if you stayed on the secure site.
One page I noticed, is the user account data page, for example https://www.primegrid.com/show_user.php?userid=306875. If from it, you click "Computers: View", or "Team: [team name]", or "Message boards: ## posts", it will take you out of the secure protocol and into the insecure one.
(I know this can also happen in other places. One thing that is hard (unnecessary) to fix is if a user writes a forum post and includes a clickable link to http://www.primegrid.com/subpage.)