This 1991 paper compared RISC (MIPS M/2000) and CISC (VAX 8700) architectures using organizationally similar hardware to isolate performance differences.
It found RISC was significantly more efficient, requiring the VAX to use an average of 2.7 times more CPU cycles for the same programs. The MIPS architecture won by using more numerous but simpler and faster instructions, along with more registers and quicker branches.