We are about to move into a new house (for us) but an old house to the rest
of the world. We noticed the cold water pressure in the upstairs master
bathroom sink was very low (and by low I mean you have to wave your
toothbrush around under it to get it wet). Another bathroom adjacent to the
master bathroom (also upstairs) had good cold water pressure along with the
rest of the house. The shower in the master bath also had good hot/cold
water pressure.

Any theories on what we should do to to correct this issue?