While their mass *by itself* will not affect the speed, the *distribution* of the mass *will*. Things rolling on ramps don't behave the same way that things falling through air do.
Their behavior depends on several factors, including density (because of air resistance, mostly), surface qualities (e.g. are they sticky, frictionless, fuzzy, have big air-trapping cones on them
, irregular, etc.), and in reference to your question their "moment of inertia".
Moment of inertia, roughly speaking, changes depending on how much of the mass is distributed near the outside of the object, rather than in the middle. You can google or look in wikipedia (though don't use it as a primary source) for a good explanation of what this concept is, though some of these a pretty complicated.
A nice simple explanation of how this applies to objects rolling down ramps can be found here: http://www.batesville.k12.in.us/physics ... e_roll.htm