hot spot
     n 1: a place of political unrest and potential violence; "the
          United States cannot police all of the world's hot
          spots" [syn: {hotspot}]
     2: a point of intense heat or radiation [syn: {hotspot}]
     3: a lively entertainment spot [syn: {hotspot}]
Source: WordNet® 2.0

hot spot n. 1. [primarily used by C/Unix programmers, but spreading] It
   is received wisdom that in most programs, less than 10% of the code eats
   90% of the execution time; if one were to graph instruction visits
   versus code addresses, one would typically see a few huge spikes amidst
   a lot of low-level noise. Such spikes are called `hot spots' and are
   good candidates for heavy optimization or {hand-hacking}. The term is
   especially used of tight loops and recursions in the code's central
   algorithm, as opposed to (say) initial set-up costs or large but
   infrequent I/O operations. See {tune}, {bum}, {hand-hacking}. 2. The
   active location of a cursor on a bit-map display. "Put the mouse's hot
   spot on the `ON' widget and click the left button." 3. A screen region
   that is sensitive to mouse gestures, which trigger some action. World
   Wide Web pages now provide the {canonical} examples; WWW browsers
   present hypertext links as hot spots which, when clicked on, point the
   browser at another document (these are specifically called {hotlink}s).
   4. In a massively parallel computer with shared memory, the one location
   that all 10,000 processors are trying to read or write at once (perhaps
   because they are all doing a {busy-wait} on the same lock). 5. More
   generally, any place in a hardware design that turns into a performance
   bottleneck due to resource contention.


Source: The Jargon File