1. A method of processing configuration data for a programmable device, the configuration data having a sequence of frames, the method comprising: identifying bits in the sequence of frames as “don't care” bits that do not affect functionality of a design implemented in the programmable logic device; comparing frames in the sequence of frames to identify at least one set of identical frame, where the “don't care” bits are deemed to result in matches; and merging each of the at least one set of identical frames to produce a respective at least one merged frame, each of the at least merged frame being associated with a plurality of configuration memory addresses in the programmable device.