As you might know, Konami realised they went a little overboard with the difficulty of the arcade version of Gradius III, so the SNES port got noticeably easier (and laggier). However, it still remains one of the hardest and most unforgiving shoot 'em ups released in its era.
That being said, the author aims to please in his attempt to surpass both preceding movies. He manages to kill almost every enemy through more efficient use of the options and faster boss fights, as well as the much needed lag reduction.
The game is completed in Arcade mode (still a far cry from the actual arcade game), which is accessed by tapping A on the main menu screen. It is strongly recommended to read the congratulatory text appearing after the end credits. ;)