What makes the Japan version of the game the fastest version? How much would I be losing if I were on English? And how much slower is VC and Emulator compared to the original hardware?
For anyone coming across this post in passing, it's worth noting that the main version differences only affects full game runs (96 exit, 95 exit etc) significantly. Switch palaces fade out about 3 seconds faster and save prompts fade in/out a tiny bit faster in the JP version than the US version. That makes JP ~21.8 seconds faster over the course of a 96 exit run. In terms of strat differences, the two are pretty much the same.
That said, the PAL version of the game has very different physics and so many normal strats won't work in that version. The overworld is also slower in PAL so if you're from a European country and are currently playing on console, I'd recommend either switching to emulator and playing on the JP version or buying a JP cartridge/SFC to play on.