[callmekit]

I wonder if you're a native English speaker?

Interestingly, in Russian "100% bigger" and "two times bigger" will have different prepositions, so it's more clear that in the first case you do sum (x + 100%x = 2x), and in the second case you do multiplication (2 x = 2x).

I'm quite sure it's the same in English (sum with % and multiplication with times), but I'm not a native English speaker.

[DougBTX]

I'm a native English speaker, I don't think I would ever say "two times bigger", sounds like bad grammar. I would read "2x the size" as "twice the size" or "two times the size", but not "add on twice the size".

So I agree with the article, "3.5 times faster (1 hour vs. 3.5 hours)" is perfectly correct, and it is OK to abbreviate "3.5 times" as "3.5x".