I've owned a pair of The One 2.5's and I have to say that they are absolutely not a "go fast shoe" in any sense, except for being lightweight. Maybe if you never exceed marathon pace, they are. For one thing, they are total marshmallows, which suck the energy out of your step. For another thing, the upper moves around a lot, and I can say this as someone with a very neutral foot strike. Also, these shoes aren't nearly as flexible as they look, especially out of the box. I have extremely wide feet, and I've run in low-profile, wider toe-box shoes almost exclusively, so I thought these Altras would be a perfect shoe for me, but in practice they were terrible. On top of that, and maybe it's just me, but the toe spring was pretty annoying, and made the shoes feel unlike any low/zero drop shoe I have worn. The one positive, I will say, is the wide toe-box, but with the loose upper, it doesn't work out like you would hope.