Watch the first 10 minutes or so of the video by Rico Mariani. The rest of the video is too technical, but what he says about "if you are not measuring, you're not engineering" are very good words.
Read the sections on "Throughput" and "Utilization" in the old
MSDN article "Understanding Performance Testing"
If you are new to load and performance testing, here are some articles to get you started on what is required to move your organization towards a measurement driven organization and your application to better performance.