DirectX 9 is actually pretty easy, and comes with good documentation.
C++ is nice, but it's so easy to write really nasty code that nobody can understand. BASIC is so much neater.
As far as I can tell, Blitz3D is about as fast as a C++ 3D engine with equal flexibility.
The biggest reason most C++ programs can go a lot faster is that they can be specially optimised for the specific game, whereas Blitz has to be able to do any type of game.
C++ is nice, but it's so easy to write really nasty code that nobody can understand. BASIC is so much neater.
As far as I can tell, Blitz3D is about as fast as a C++ 3D engine with equal flexibility.
The biggest reason most C++ programs can go a lot faster is that they can be specially optimised for the specific game, whereas Blitz has to be able to do any type of game.