Further to this, from MacKiDo, point #6:
"The floating point of the 603 and G3 had only a 32 bit multiplier (ALU) -- so for floating point multiplies it took two passes (2 cycles) to do a 64 bit floating point operations. The 604's had a full 64 bit multiplier, and so did better at floating point math performance than the others (up to twice as fast). The G4 has picked up the 64 bit ALU, so the G4 should have better floating point performance than the G3."
"The floating point of the 603 and G3 had only a 32 bit multiplier (ALU) -- so for floating point multiplies it took two passes (2 cycles) to do a 64 bit floating point operations. The 604's had a full 64 bit multiplier, and so did better at floating point math performance than the others (up to twice as fast). The G4 has picked up the 64 bit ALU, so the G4 should have better floating point performance than the G3."