It seems that gbc works around the noime halt with if&ie bug (next pc byte is read twice), by autoinserting a nop after every halt. This means normal halts will take 4 cycle longer on the gbc, and noime halt with if&ie will take a total of 12 cycles (4 cycles for the halt opcode, 8 cycles for the two subsequent nops). Note that I have not done any tests on the original game boy (dmg), only on the gbc.
