We study the approach of the speed of sound towards the value cs = 1/3 at high temperatures in a general class of strongly interacting theories. This class includes theories holographically dual to a theory of gravity coupled to a single scalar field, representing the operator of the scale anomaly. We show that quite universally the conformal value c_s~2 = 1/3 is approached from below and give a generic argument for why this has to be so.
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