Compounds of 速い

• 速い
  (adj-i) (1) fast
  quick
  hasty
  brisk
  (2) early (in the day, etc.)
  premature
  (3) (too) soon
  not yet
  (too) early
  (4) easy
  simple
  quick
  (P)
• 素速い
  (adj-i) (1) fast
  quick
  prompt
  nimble
  agile
  (2) quick (to understand)
  sharp (judgement)
• 足速い
  (adj-i) swift-footed
  light-footed
• 耳が速い
  (exp) being quick-eared
  having sharp ears