[hnuser123456]

That's just sloppy language and you got used to it. Twice as fast means twice as fast. Two times faster means two times faster. One time faster would mean twice as fast. 0.5x faster would mean 50% faster or 150% as fast. 0.5x slower would mean 50% slower or 50% as fast.

[bomod]

And what would 2x slower mean?

[hnuser123456]

reverse time

but really, relative to something else, i guess it would be 0.33x as fast, because it would take two times more time, or 3 times as long