People like to talk in percentages when it's obviously unclear what it means, and they frequently get it wrong. It gets even better when people start switching

People like to talk in percentages when it's obviously unclear what it means, and they frequently get it wrong. It gets even better when people start switching between percentages and "percentage points" referring to a measure that's in percentages originally. Unfortunately, most of those things are easier communicated and harder to get wrong if you try speaking in a more natural way. This is now "twice as fast" or "2.1x faster" is much clearer and can't go past zero :) Similarly, I think it'd help to switch back from percentages to actual factors (119% = 1.19), and saying "we reduced the time for the computation by 1.19 of original time" would clearly show what's wrong (and saying "by 1.19x" would signal how it's a small reduction, so it's wrong as well). Finally, I am 94.8% certain people will keep using percentages even where inappropriate, and with too much precision too!