javascript – Why Facebook pages are so heavy?

When I open the simple links of Facebook, my browser downloads many files. Some are js files, relatively large.
Once I downloaded 30 MB when opening a page that I manage.
The following image shows a simple publication of Facebook, which downloaded 10.9 MB locally.
Why is it happening? Why Facebook is heavier than any other website?
Every time I open it, I have to wait a long time (my internet is a bit slow).
I am using Chromium Version 57.0.2987.98 Built in 8.7, running on Debian 8.8 32 bit

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