the short answer is “UltraHLE” – N64 emulation is very inefficient, and you usually have an option between painstakingly reimplementing a lot of undesirable aspects of the original hardware with degraded sound/timing/blending, or implementing equivalent function calls, and (like PS2 emulation, its hideous RDRAM brother) most of the code that the community has produced for doing so has been a) constantly rewritten and b) in its agreed best forms was until recently tied to like, DX9 implementations that are themselves not that portable
libretro has a tendency to claim they’ve reinventing the wheel (as does a lot of modern emulation, granted, they aren’t as bad as the FPGA community in that regard) but ParaLLEl – Libretro is honestly the first portable, modern N64 emulator that passes muster in a lot of ways (which is not to neglect the historical contributions of Project64, sixtyforce, and so on), and it’s too new and incomplete for Nintendo to somehow use