Im using snes9x v1.7x

It doesn't so the game does not save after beating the game

Have a read at this https://www.speedrun.com/smw/forums/z84zv maybe it anwers your questions.

ty, i saw that thread after posting this one. another question, the run ends right when you see peach after defeating bowser, correct? or is it when she touches the gound?

I am pritty sure I don't really run the game competitively

Yes, it is on the frame Peach appears out of the clown car