@siwowes just remember that Mrneo240 port is a very rough, unpolished and straightforward version of the game for the dreamcast, means that the entire source code and rom game loads in the main console ram from the start and all the time stay there (16MB)
Mario 64 rom size is about 8MB, so you need at this point mods that can't exceed that rom size to properly work.
At least until a new well made dreamcast port exist that uses the full potential of the console.