On high traffic pages where bandwidth may be a concern, we suggest using the API to create a custom solution that uses less bandwidth. Hitting our API still counts towards your total monthly bandwidth usage. The advantage comes from using the API to pull less content, or excluding high bandwidth content like images and videos.
To get a rough idea of how much bandwidth a custom API implementation might use, load the API implementation in a web browser and use Firebug to see how much bandwidth is used on page load. Multiply that number by the number of page views you anticipate to get your total bandwidth usage estimate.