I have not heard of a Casio Z75.

Do you mean Z57 or Z750


SD cards and speed.

A high speed memory card will have no effect on shutter delay. Most of the delay time is caused by the autofocus mechanism.

A high speed memory card will usually perform better on DSLR (digital single lens reflex) cameras, with regard to the high speed continuous shooting.

They seldom do anything for other digital cameras.
There are a few exceptions; such as the Canon S2 IS and the just introduced Panasonic FZ30. These have continuous shooting ability.

Many Sony cameras must have high speed (Pro version) memory stick to meet the specifications for 640x480 video at 30 fps. That is because the normal memory stick is too slow.