Speed of camera itself highly depends of buffer memory. After sensor accepts light and processor converts data into photography, it doesn't go directly into the memory card. Reason for that is still slow interface between the camera and memory card. To avoid waiting while data is being written on card, between sensor, processor and memory card there is memory buffer that is nothing but fast RAM memory whose purpose is to immediately accept more photographies, that will later be slowly distributed on memory card. Basically, the larger the buffer is, the work with camera is faster and we are able to make more photographies in shorter time.

Graphical explanation of data processing