Rate of hydrogenation
Are you asking about catalytic hydrogenation or non-catalytic hydrogenation (e.g. diimide)?  For the time being, let's assume that your question is about the catalytic process.  All the catalyst does is lower the activation energy required to reach the transition state (TS) and the TS will look about the same independent of which isomer you start with.  Therefor, ground state stability differences between the two olefins will determine which isomer reacts faster.  Since trans-olefins are generally more stable than their corresponding cis isomers, it will take more energy (the difference in stability between the cis and trans isomers) for the more stable (lower energy) trans isomer to reach the TS, and less energy for the cis isomer to reach the TS.  Consequently cis isomers react somewhat faster than their trans-counterparts during catalytic hydrogenation.  I suspect that the same considerations would apply to non-catalytic processes.

As an aside, remember that in the catalytic process, depending upon catalyst, temperature, solvent, pressure, etc.; many other things can be going on, such as cis-trans isomerization of the starting material, positional isomerization, etc.  So if the reaction conditions are not chosen carefully and 1) if cis-trans isomerization is faster than hydrogenation and 2) let's say the cis isomer reacts 100 times faster than the trans; then both isomers could appear to give the same rate of hydrogenation because all hydrogenation would proceed through the cis isomer.