Be aware that any temperature rise from speed increase may encourage runback ice to form on unprotected surfaces and particularly near controls.
Many factors determine how and where ice will form on a particular aircraft. Remember that the tailplane could be more prone to icing (relatively thinner section), and thus as speed changes the tail could accumulate more ice due to local AOA change from the change in downwash / prop swirl.
IIRC, where a surface is prone to icing, then the rate icing could be higher with increasing speed due to the rate at which water droplets are encountered (comments?). Also, the larger (denser) droplets may penetrate the relative airflow more easily hitting the airframe surface forming ice? Thus in these conditions the aircraft would have less time to exit the conditions. Conversely flying faster could exit the conditions quicker, but don’t forget that you can change altitude, which is often the most effective way to exit icing.
Most of the variables depend on the aircraft type; check the manufacturer’s recommendations particularly for holding and approach speeds. Often a recommended speed increase is to maintain the stall margin and not for the ammount of ice accumulation reasons.
Whilst the originating question might be hypothetical, a more appropriate one would be to ask which speed is the best to reduce the threat of ice accumulation.