I was talking crap in my last post. Last night I had a stage 5 run on the International version in Mame. Then went upstairs to compare it with the JPN PSX port. The latter was much faster, much crisper, and whole lot nicer to play. I'm talking everything was quicker, not just bullet speed. I don't really know what I'm doing with Mame, so there's a chance I didn't have the first game optimised for correct speed. But damn, what a difference!
I'll grab the JPN ROM later to compare with the Int version. Oh, I did beat my PSX score (to follow).