You may need to repack the BB, but since the cranks are shorter, you will have less leverage than you did on your old bike.
Since it sounds like you transferred over the same wheels, then the BB seems like the most likely culprit.
The heavier bike will impact you some on acceleration and hill climbing, but once you are rolling on the flats, you should be fine.
To check out whether it could be just the length of the crank, look at Sheldon Brown's gear calculator and at his explanation of "gain ratio" to see what I am referring to.
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Slow Ride Cyclists of NEPA
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