Synonyms of fastest

1 Syllable
brisk, hot, snap, swift, fleet, quick, pdq, flying
2 Syllables
ready, breakneck, presto, flashing, snappy, racing, fleeting, hasty, dashing, rapid, hurried, chop-chop, pronto, nimble, speedball, winged
3 Syllables
active, electric, agile, posthaste, double-time, hairtrigger, screamin', velocious
4 Syllables
supersonic, hypersonic, expeditious
5 Syllables
accelerated, expeditive