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Because usually there would be some lag time for the camera's electronics to actually process your actions and finally snap the shutter.

My SLR has no lag time and there's no caching there. It can just be "fast" too. Simplest explanation is always the best, and such.

SLRs work much differently and the lack of a delay is actually one of their selling points. A bit more on that topic:

Those fast electronics cost extra time and money to design and build.