10 ain't done till Chrome won't run...
It is very easy if you own the operating system to make sure your browser works faster than the opposition's browser...undocumented APIs that only your own browser can use.
Just like the old days, in fact, "DOS ain't done till Lotus won't run"...for those with long memories.
Now you may say that they could have speeded up IE long ago, but at that point, the main aim was to try to slow the wholesale migration of computing onto the web, leaving the PC little more than a thin client.
Now that is irreversible, they don't mind speeding it up to keep control of the Internet entry point on PCs.
But I'm just an old fogey, take no notice.