Term Kind Topic What it is
Cost per Request metric Cost per Request Total cost divided by units of business value — the metric that makes cost comparable across time, scale and design options.
Idle Cost concept Cost per Request The portion of infrastructure spend incurred regardless of traffic, which determines how cost per request behaves as volume changes.
Pass-Through Cost of Goods Sold Third-Party Unit Cost, Supplier Pass-Through Term concept Cost per Request The part of the cost of serving one unit that is paid to a third party per transaction, which infrastructure optimisation cannot reduce and which eventually decides whether unit cost keeps falling.