Most people access Facebook via the main site and that's the all singing, all dancing version. As well as seeing what your friends are up to, the silly games and adverts work just fine.
At the other end of the scale, there's a very simple site that's really intended for mobile phone users. You can use it from your PC as well and it's very fast and doesn't hang up or crash like the main site. There's no "chat", games or adverts.
Then there's a happy medium which they call Facebook Lite. It does have chat and adverts. Not made it crash yet.
Finally, I discovered what they call the Touch Site which is another medium weight version. I'm not sure what its intended mission is. I suggest you just try it and see if you like it!