I also faced this error many times but after performing some necessary tasks i fixed it, which r described below:
First, small size of RAM makes computer slow.
Secondly, corrupt windows registry causes freezing in computer.
The third most important thing that you can do to optimize your Facebook is to optimize your internet connection.
So it is recommended you use a system utilities software that provides the feature of internet optimizer.
Also remove unwanted add-ons/extensions from your browser.
It is also recommended to clean system junk and browsers junk.
The above guidelines allow you to Avoid Facebook Freezing and keep your Windows properly maintained.
I got some help from this article to avoid Facebook Freezes.