Excellent speed for a consumer-oriented digital SLR.

The Nikon D40x's performance was quite fast overall. Start-up time is slowed to 1.1 seconds (still not too bad) if you wait for the LCD display to appear, is only 0.4 second otherwise. Shutter lag is quite good on average, and "prefocus" time (half-pressing and holding down the Shutter button before the final exposure) is also above average at 0.095 second. Shot-to-shot cycle times are very good, at about 0.49 second for large/fine JPEGs, and the camera can capture over 20 frames at this rate. Continuous-mode speed is slightly above average at about 3.03 frames/second, for 7 shots in succession, in large/fine JPEG mode. RAW mode isn't really any slower, but has a slightly shorter burst length of 6 frames. The flash recycle time is about average at 5 seconds after a full-power shot. Connected to a computer, download speeds are exceptionally fast, so you won't feel a need for a separate card reader. Bottom line, the Nikon D40x's performance is above average for a consumer-oriented digital SLR, and is responsive enough for most action shots.

Battery
Very good battery life with the custom lithium-ion battery pack.

The Nikon D40x uses a custom rechargeable lithium-ion battery for power, and comes with a charger.

Even though runtime is quite good, I strongly recommend picking up a spare battery pack and keeping it freshly charged and on-hand for extended outings. (Digital camera batteries are firm believers in Murphy's Law, always running out of juice just as the best photo ops of the day are available!)

The table above shows the number of shots the camera is capable of (on a fresh set of fully-charged rechargeable battery as appropriate), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))

Storage
The Nikon D40x accepts SD/SDHC cards, though no card is included.

The chart above shows how many images can be stored on a 512MB card at each size/quality setting. We strongly recommend buying a large capacity SD/SDHC memory card at least a 1GB card, preferably a 2GB or larger one, to give yourself extra space for extended outings. (Check the shopping link above. Cards are really cheap these days, so there's no reason to skimp.)