My MacBook was sub-par the other day, so I looked at the activity monitor. There were 5 different Facebook processes (each running in a web page in Safari) that were each taking up between 1.2 and 1.5 GIGABYTES of RAM. (Each Facebook page corresponded to a different Facebook group I'm in -- don't ask.)
My poor little MacBook only has 16 GB of RAM, so these five web pages were was taking up 40% of it. Facebook must have get kickbacks from the computer memory companies.
My MacBook ran much better after I closed those pages.
IMO either FB has the world’s crappiest code. Or they are using it to steal info from your computer.
Or both.
And they are not alone in that theft.