They also did measurement with the same machine. # of instructions and performance are not 1 to 1, but the result they had was pretty close.That metric by itself is meaningless. what are the IPCs (instructions-per-clock) of the CPUs?
This is what they saw from a year earlier when they tried both MIPS and LoongArch on 3A4000. Note here that MIPS had 15.8% more instructions but execution time was just 12.4% longer.
Also note that in the past year, they improved performance of LoongArch so that MIPS now require 20% more instructions on average.
So while RISC-V may not require 31% more execution time, but it will take quite a bit longer. With a reduced instruction set, certain calls will just result in multiple instructions on RISC-V that might be done through 1 instruction on ARM.
Of course, you always want to balance complexity vs performance. RISC-V processors do consume less power than ARM.
As RISC-V continues development, I think you will see more instructions and performance improvement.