>There could be zillion of factors. The current work load on the server, which plan the optimizer chose for the query, how many I/O operations (page reads) were involved in the query, etc.
>
>Although the difference in numbers is too drastic.
>
>Take a look at this blog post Glenn Berry Query Optimization Diagnostic Queries
>and try running them to analyze the situation.
>
>Also, are you using ad-hoc query or stored procedure with the compiled plan?

I have included the technical reference in Message #1493518.