Performance may sound like a no-brainer when it comes to talking about acceleration however people look at different metrics when it comes to determining the performance improvements an acceleration solution will provide.  Last week I met with two different customers to determine the performance improvements that WebAccelerator would provide.  Customer 1 was mostly interested in end user response times, they have a number of branch offices around the world with latency ranging from 0 to 400ms.  The speed with which Sharepoint pages and documents would download at various speeds and latencies was the critical performance metric.  I am happy to report that the performance testing revealed roughly a 50% reduction in document download times.  Customer 2 was interested in measuring the hits per second the back could process to gauge the performance improvement.  In this instance the hits per second increased from about 200 to 2000. 

Will customer 1 see an increase in hits per second and will customer 2 see a reduction in page and document download times - probably however this isn't what is driving their need for an acceleration solution.  The metric used to determine performance gains is going to vary based on what is driving the need.  Are customers complaining about slow download times?  Have you recently acquired a new company resulting in more people accessing an already loaded application?  The choice of the performance metric is yours.  The trickier part comes in determining how much improvement is good enough. 

It helps to have a quantitative as opposed to a qualitative target.  When asked what the goal of testing should be one customer replied "I want my customers to be happy."  While it is noble to want happiness it unfortunately isn't a valid performance metric.   Once you have a quantitative metric make sure it is realistic and achievable, if the page is taking less than 1 second to download wanting a 50% reduction in response time may not be realistic.