PDQ
abruptly
apace
aphoristically
at once
briefly
brusquely
compendiously
concisely
crisply
curtly
decisively
directly
economically
expeditiously
forthwith
immediately
in brief compass
in no time
instanter
instantly
laconically
on the instant
on the spot
peremptorily
pithily
pointedly
precipitately
pretty damned quick
promptly
pronto
quickly
right away
right off
sententiously
shortly
smartly
sparely
speedily
straightaway
straightway
subito
succinctly
suddenly
swiftly
synoptically
tersely
with all speed
without delay
without further delay
preliminarily