Synonyms for Cracking:

adj.

snapping (adjective)
crashing, Slamming, flapping, Thwacking, Bumping, rapping, tapping, thumping, knocking, bursting, whacking, smacking, Clacking, Clicking, snapping, Slapping, clapping.

adv

quickly (adverb)
frenetic, hurried, like mad, quickly, fast, hasty, in a flash/like a flash/quick as a flash, like a shot, rapid, urgent.

n.

cushdy, ace, singular, select, plum. act (noun)
fracture.
cracking (noun)
dandy, slap-up, fracture, swell, noisy, bang up, keen, neat, good, bully, nifty, great, not bad, peachy, groovy, smashing, corking.

v.

blemishing (verb)
Disfiguring, hurting, Hacking, staining, spoiling, scoring, Discoloring, marking, Scarring, blistering, Checking, Notching, scraping, Flecking, Distorting, defecting, Gashing, Blotting, damaging, Defacing, Fracturing, Scuffing, Freckling, Kinking, splotching, Tarnishing, Tainting, Abrading, scratching, chipping, Deforming, Slitting, Specking, Dotting, Nicking, Flawing, Blemishing, spotting, Marring.
notching (verb)
splitting, Indenting, Incising, serrating, cleaving, cutting, Chinking.
snapping (verb)
crashing, Slamming, flapping, Thwacking, Bumping, rapping, tapping, thumping, knocking, bursting, whacking, smacking, Clacking, Clicking, snapping, Slapping, clapping.

Other synonyms:

bang-up
bang up.
Other relevant words:
fast, noisy, corking, hurried, rapid, ace, dandy, singular, plum, good, hasty, select, neat, nifty, groovy, frenetic, bully, fracture, not bad, quickly, cushdy, great, peachy, slap-up, swell, urgent, smashing, keen.

Usage examples for cracking

  1. When we passed before, this ground was dry, parched, and cracking open. – Incidents of Travel in Yucatan, Vol. I. by John L. Stephens
  2. From time to time he listened intently for possible sounds from the distance where his friends might be encamped, and might fire off their guns at seeing his light; or he listened yet more intently for sounds nearer at hand: but all was still, except for the occasional cracking of the wood in his own fire, and the slight whistle of the breeze as it crept past the stones on the kopje. – Trooper Peter Halket of Mashonaland by Olive Schreiner
  3. But in this I was too generous; having forgotten my pistol- wound, and the cracking of one of my short lower ribs. – Lorna Doone, A Romance of Exmoor by R. D. Blackmore