fast time scale vs time scale

fast time scale and time scale both are nouns.

Word	Noun	Adjective	Verb	Adverb
fast time scale	Yes	No	No	No
time scale	Yes	No	No	No

As nouns, time scale is a hypernym of fast time scale; that is, time scale is a word with a broader meaning than fast time scale:

fast time scale: (simulation) the time scale used in data processing when the time-scale factor is less than one
time scale: an arrangement of events used as a measure of duration

fast time scale (noun)	time scale (noun)
(simulation) the time scale used in data processing when the time-scale factor is less than one	an arrangement of events used as a measure of duration