The same issue exists in most European languages, and there are two schools of thought. Some people want to use language that is logical and consistent. For th

The same issue exists in most European languages, and there are two schools of thought. Some people want to use language that is logical and consistent. For them, "3.5x faster" means the same as "350% faster" and "4.5x as fast". Others believe in convenience and redundancy. They think that "4.5x faster" means the same "4.5x as fast", because the numbers are the same. Many of them don't like expressions such as "X% faster" for X >= 100, because the numbers tend to be misleading. I used to be in the former camp when I was young. Today I'm middle-aged and lazy. When I see "3.5x" in the text, I assume that it means "3.5x". I don't want to read the text carefully to determine that you actually meant "4.5x" when you wrote "3.5x". I interpret the "faster" part as redundancy. It tells me that we are talking about speed and that the thing we are talking about is faster than the baseline.