Inner Loop
     / ˈinər lo͞op /

(def.)

1. One of two freeways in the Cyber Corridor region.  Both Washington, D.C. (I-495) and Baltimore (I-695) are circled by a Beltway, and in each case the clockwise-moving road is referred to as the Inner Loop.

2. The Inner Circle.  Those in the know or connected.

3. In a repeating algorithm, the most often traversed section.  It is therefore also the critical code to improve performance.  en.wikipedia.org/wiki/Inner_loop