Synchrony is an important aspect of social behaviour. Prior research has observed a synchrony-bonding effect, suggesting that synchronised action may be an efficient way of creating and maintaining social affiliation. However, most of the theories attempting to explain this synchrony-bonding effect rely upon higher-order social cognition. Relatively little attention has been given to the perceptual experience of synchrony, and the low-level perceptual mechanisms involved. One possible mechanism that could explain some of the effects of synchrony is that of processing fluency. In two pre-registered experiments, we test the novel hypothesis that synchrony (congruent movement) is easier to process than non-synchrony. We find an effect of speed congruency, but not direction congruency, on performance in a Flanker task with animated Gabor patches. The stimuli presented here are continuous vectors, best understood as derivatives of the periodic movement seen in naturalistic stimuli. As such, incongruent speed is most likely to be experienced while perceiving non-synchronised periodic movement, suggesting a greater processing load during the perception of that movement. Crucially, the effect observed here does not rely upon social stimuli, and may operate at an early stage of perceptual processing. This is an initial step in establishing a novel theory of the synchrony-bonding effect, based upon the principles of processing fluency.