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 hotlinks). 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.