Gilbert Arenas' Child Support Victory Against Ex Laura Govan

Gilbert Arenas got a huge assist from the judge in his child support case ... his monthly payments to his ex were just slashed big time.

Sources close to the former couple tell us ... Gilbert's child support checks to his baby mama, Laura Govan, will now be under $10k a month ... a huge drop from around the $40k he claimed he was paying. Arenas has recently said he's not as rich as everyone thinks ... and apparently there's some truth to that.

Gilbert admittedly has no chill, though ... so he took the opportunity to gloat about his big win in court and troll Laura at the same time.

Sources close to Govan tell us she has no idea why Arenas continues to insult and torment her -- since she's not doing it to him -- but all she wants now is for him to leave her alone.