I'm not sure I've ever seen anything described as being '1x' faster, without any fractional part. It's such an uncommon usage, I really don't think you can categorically declare that '1x faster means twice as fast'.
There is a very distinct difference between "faster than" and "as fast as" which should be very clear now.
It's completely ambiguous with potentially significant costs for misunderstanding, but people refuse to make themselves clear, just because.
What I meant to say in my parent comment is not the use of "faster" vs "as fast" in English, but that usually in those benchmarks "Nx" means N times the speed of the baseline.
Kevin Decker, who did the site in TFA, is a native english speaker, and yet he writes "1.5x faster" to mean baseline1.5 (and not baseline + 1.5baseline).
So clearly it's not so "unambiguous" whether you can use faster in this way or not. And in fact, I've never seen any of those benchmarks where "Nx" doesn't mean the final value is N*baseline.
Very unintuitive.
"faster than" != "as fast as"
A is 50% faster than B == A is 150% as fast as B