I noticed that the website is rather slow. Now theres not much I can help with to make retromags faster without diving into the codes.
But there are two tips I could give you.
1. Place all your internal css styles in a external sheet (The browser will download it and cache it so people won't redownload the same code everytime the visite a page)
2. create a htaccess file in your root dir protect it and let it cache your images,css,html,php etc.
Those two tips will make this website a lot faster believe it ore not.
Also the downloads hosted by retromags, will slowdown the webpage when lost of people are downloading at the sametime.
So the best way to counter that is by creating a speed limit for downloads.