Bigger planes appear to fly slower than smaller planes at the same real speed (e.g., perceived speed).

If you are asking about real speed (relative to the air mass), the ability of the plane to fly slowly depends on the lift generated by the wing and the weight of the plane.

Since pattern planes use symmetrical wing profiles at almost 0 incidence and wingspan is limited to two meters, we can rule out those three variables. Then, you can definitely say the flying speed will be most affected by the wing thickness (much more than any landing gear and cheek cowl), and chord (Reynolds number). Therefore, fat and wide wings will fly slower than thin narrow ones. By the way, the wing chord also affects aspect ratio, but we can use one or the other in our calculations since they are matematically equivalent (given the almos fixed wingspan around 2 meters).

Now, given the same wing, a fatter fuselage with side cheeks, fixed landing gear and lower pitched propeller will definitely be slower than the opposite side around.