If you take the raw transaction times for the database and workflow tasks, then factor them against the average processor utilization for these same workloads, you see that Windows XP consumes roughly 7.2 and 40.7 billion CPU cycles, respectively, to complete a single pass of the database and messaging workflow transaction loops on our quad-core test bed. By contrast, Windows Vista takes 10.4 and 51.6 billion cycles for each workload, while Windows 7 consumes 10.9 and 48.4 billion cycles. Translation: On quad-core, the newer operating systems are at least 40 percent less efficient than XP in the database tasks and roughly 20 percent less efficient in the workflow tasks.
Be careful when a loop exits to the same place from side and bottom.