[ENicolas]

It has to do with hardware memory: more and faster buffer memory is more expensive. Also compression must be taken into account for JPEG: most companies list their JPEG throughput for the highest compression and lowest quality.

At 7fps and around 24 RAW in the buffer before it has to flush to the card the K-5 seems fairly respectable to me.

[Anvh]

ENicolas, you missed my comment before you.
RAM is the fastest piece of hardware in it and image processing and "flushing" are done at the same time by different processors.
The K5 use 2x DDR2 ram's just look up the minimum speed for those

found some hard data about speed indication.
the processor in the K10D/20D uses 750MB/s for his RAM in the K7 and K5 there is a newer processor.