bum

1. To make highly efficient, either in time or space, often at

the expense of clarity. "I managed to bum three more

instructions out of that code." "I spent half the night

bumming the interrupt code." In elder days, John McCarthy

(inventor of Lisp) used to compare some efficiency-obsessed

hackers among his students to "ski bums"; thus, optimisation

became "program bumming", and eventually just "bumming".

2. To squeeze out excess; to remove something in order to

improve whatever it was removed from (without changing

function; this distinguishes the process from a

featurectomy).

3. A small change to an algorithm, program, or hardware

device to make it more efficient. "This hardware bum makes

the jump instruction faster."

Usage: now uncommon, largely superseded by v. tune (and

tweak, hack), though none of these exactly capture sense

2. All these uses are rare in Commonwealth hackish, because

in the parent dialects of English "bum" is a rude synonym for

"buttocks".

[Jargon File]