Is this site safe to use on your macbook?

[magic.smile.x]

I get quite bored of doing the same thing on the computer all day (Youtube, Twitter, Facebook, tumblr etc) you get my point. So one of my friends told me that http://www.meez.com/home.dm Is a safe site, and it's fun to use! I've used it a few times on my grandparents computers, or my brothers laptop and a lot of people do say its safe. But I find whenever I use it, It slows down my computer. I've looked it up and some people said it's bad for your computer. But I have no idea! Can someone please tell me if Meez is a safe site to use?