Joystick events

Hello.

I’m using the SDL as a miltiplateform inputdevice library.
I’d like to use only a part of the SDL : joystick events.

In order to be able to use it I need to use :
SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK)
using SDL_Init(SDL_INIT_JOYSTICK) doesn’t give any events !

Is this normal ?
Does using SDL_INIT_VIDEO can have performances impact on my rendering system ?

Thanks a lot.

jOan