By the way: during loadings the screen "flashes" in black, it happens also to you?
Yeah, it does the same here. It's because, even with a 4MB Minimig, there's no RAM for preloading, so the Amiga has to switch between the OS and the game to load the files, since the game is not multitasking (when the game boots from disk, it takes over the machine and disables the OS: most amiga games work this way).
However, it loads WAY faster than any ADF or floppy version. Try ADFs with a 7Mhz Amiga and you'll feel how you get older while it loads.
You can also use AmigaDOS instead of booting to WB to save some RAM and you could get some less flashing (not sure).