In the defaul japanese version of the game theres a diference on the bosses hp that compared look like this

Hits per boss on diferent regions

.....................................|----------Japan-------|------USA------|----Europe------
--------------------|------------------------|----------------------------------

The hits diferences can save minimum 15 secs on a run.

°Vs Slot Machine since after the 6 ball you have to wait for his animation.

°Vs Dancing Bunny 5 hits talk by Themselves.

°Vs Sun machine 1 hit more can take a lot if the boss decides to attack with fire because at this point fire animation have 3 shots and Sun RNG can even do it a few times in a row losing more time.

Total Hits in a run |--------Japan--------|------USA------|----Europe------ on diferent version|---------60----------|-------67-------|-------67--------

At this point playing the japan version is better for time vs bosses but being the default japanese version it is still a Standar/Default run, idk if it will be cange in the future to get diferent region speedruns or it will stay the same, anyways for now this can help to clear faster the game for default runs