Synonyms of post-haste in English:

post-haste


See definition of post-haste

adverb

1‘he departed post-haste for Venice’

SYNONYMS
as quickly as possible, as soon as possible, ASAP, without delay, quickly, very quickly, speedily, swiftly, without further ado, without more ado, with all speed, promptly, immediately, at once, straight away, right away, directly, forthwith
informal double quick, p.d.q., pretty damn quick, pronto, before you can say Jack Robinson, straight off
archaic straight, instanter