Originally Posted by Moyene Corniche

On this 54cm, you are perched on top of the bike, whereas you would / should be nestled in on a 56cm.. Even if your TT is 57 ( doesn't look it ) your bike's geometry is still preventing you from attaining a flatter more efficient position when on the hoods at the front or off the front.
Your breathing is also restricted by being crunched up.. That bike may feel responsive, but ( as you say ) if you need to temper the front ends twitchiness, then you will find that in a crit corner mid pack at full speed, needing to adjust your line quickly will result in going down...