My understanding is that the massively unrolling loops thing had to do with how different branches felt versus previous consoles. Compared to filling an I$ lin

My understanding is that the massively unrolling loops thing had to do with how different branches felt versus previous consoles. Compared to filling an I$ line (somewhere in the many dozens of cycles on an N64), a branch mispredict was very cheap. However branch mispredicts were very visible. Delay slots were present in the ISA to decrease their cost and the pipeline stalls were noted in pretty much all literature on RISC at the time. On top of that, the N64 really didn't have great performance monitoring tooling, but was complex enough of a memory hierarchy to have really benefited from such tooling had it been available. It's pretty hard to understand the system effects pieces of code have without that.