A speedup is the event of something becoming faster — either something physically moving faster, or a process happening at a quicker rate. If a factory was making 100 units an hour and now makes 130, that change is a speedup in production. If a slow economy starts growing again, newspapers call it a speedup in growth. It is the opposite of a slowdown, and the two words are used as a matched pair, so if you know one you know how the other behaves. Notice that it names the change, not the state: a speedup is the going-from-slow-to-fast, not the fastness itself. It is countable — a speedup, two speedups — and it usually comes with in or of to say what got faster: a speedup in hiring, a speedup of the assembly line. It is a fairly plain word that lives mostly in news, business and technical writing rather than in chat; in ordinary talk people just say "things got faster". Two corners worth knowing. In labour history, a speedup means something specific and unfriendly: management pushing workers to produce more in the same hours without more pay — that is why the word appears in old union arguments with a sour tone. And in computing, a speedup is a measured number, how many times faster one version is than another: "a 4x speedup". Also note the spelling. The noun is one word, speedup (sometimes hyphenated, speed-up). The verb is two words: speed up. So "we need to speed up" but "we need a speedup".

加速、加快（速度或進度變快這件事）。跟 slowdown（減緩）是一組相對詞。工廠講「加快生產速度」、經濟講「成長加速」都用它。