Don't buy the Japanese cart if your only rationale for doing so is that it'll be faster because there's less text to scroll through. It's not actually faster.
(Even though there's less text, that text scrolls way slower so it ends up actually losing time compared to English text, even with cutscene skip. That said, if you already have a Japanese cart, you can switch the language to English to save some time.)

Change the graphics to "Classic". This has two effects: First, room transitions seem to be a frame shorter with Classic graphics as opposed to new graphics (?). Second, with Classic graphics, this block that blocks the passageway in the jail will have no collision, allowing you to leave immediately without having to talk to Mahin: