Short version: Do not speedrun this game on RetroArch, it has settings which can cause inaccurate emulation. We recommend using current versions of Nestopia, FCEUX, Mesen, and higan/bsnes; or, OpenEmu with one of the those cores.

Full version: For the time being, we will not accept runs on RetroArch due to the potential for large scale inaccuracy which was recently discovered in runs of another game. It was detected when the run didn't experience what some call 'NES slowdown' during a well-known circumstance that should produce slowdown. The runner claimed to be using RetroArch.

In TLOZ, the most obvious manifestation of NES slowdown is on overworld screens with Octoroks and Moblins, and in the Blue Darknut and Turret rooms in Level-8. Slowdown also happens, less obviously, during screen transitions and while loading caves and dungeons.

The exact cause of inaccuracy is yet unknown, but the affected runner claimed to be using RetroArch with some of the latency reduction features turned on. RetroArch is actually a front end program that basically runs other emulators' cores (the program that emulates hardware). There has been limited investigation running the circumstance above on NES hardware, FCEUX, mesen, bizhawk, bsnes, and in RetroArch running each of those cores on default latency settings. Tests all produced more slowdown than the inaccurate run in question.

So, while RetroArch is at least capable of being accurate, there's still a question of whether and which of its front end settings employed by that runner created the inaccuracy. Not knowing the causes means we don't have a way to recommend correct settings in RetroArch.

I would prefer to not ban RetroArch under mere suspicion, but the burden on moderators to examine lag in runs is too high and we'd rather our runners not risk their runs using potentially inaccurate emulation. Given the number of other accurate and user-friendly emulators available the simplest solution right now is to warn runners off RetroArch and continue recommending current versions of Nestopia, Fceux, Mesen, Higan, and OpenEmu (with one of the those cores).

RetroArch is a shell that can load many Emulator Cores - including the FCEUMM, which is lag accurate. Additional research should be done to reverse this mandate, or expand upon it. RetroArch is a good tool overall, but if it cannot produce accurate times in ANY of its configurations, it must continue to stay banned.