1. No one trusts Google to be an impartial judge of speed.
2. Increasingly, Google is inserting itself as a non-neutral third party between the end user and creator/developer. Power lies asymmetrically with Google, and threatens both creators & users.
If anyone from Google is reading, this incremental but definite appearance of a power grab by Google will only draw more regulation
We should really just stop using Google so much. You go first, I can't be bothered to switch!
That's a recently very popular idea, but in this general form it is simply untrue. It depends on the specifics of any regulation.
We can regulate oligopolists in a way that doesn't affect anyone else.
Google wants there to be lots of web sites, lots of web pages. So using someone's web site should be more convenient than using that someone's facebook page. How to achieve that? My guess is that Google has done some research into that, and a focus group or whatever named slowness (or an expectation of slowness) as a disadvantage of the web compared to facebook.