instantaneous (adj.)

• alert
• apt
• brief
• compact
• compendious
• concise
• curt
• curtal
• decisive
• expeditious
• fast
• immediate
• instant
• little
• low
• momentaneous
• momentary
• presto
• prompt
• punctual
• quick
• rapid
• ready
• short
• speedy
• spontaneous
• succinct
• summary
• swift
• synoptic
• transient
• transitory