Hi Razaro, thank you for your answer, yes you are completely right, it might take a bit more than few minutes to solve such issue 
Sorry for the caps, i will change title tomorrow so that the post won't bump too fast.
For solutions, on Github, some guys recomend to do this SQL command line :
UPDATE ps_cart_rule SET cart_rule_restriction = '1' WHERE ps_cart_rule.id_cart_rule > 0
Only problem, is that :
1/ i would need to automatize/run that command line every hour or so, do you think this would be possible through cronjob ? (that may sound stupid question but i'm no programmer)
2/ i have to adapt a bit this command line so that ONLY SOME SPECIFIC cart rules names would become incompatibles, but only some of them. ex : some cart rules with name "SEXYCODE" (cart rule with name SEXYCODE have random generated code) . Maybe you can help to give me the SQL query line i could write to do so (sorry again, but i'm beginner for programming) ?
I think if i can combine kindda Cronjob + SQL query this should be sufficient. I won't have 20Gb of cart rules OMG, your customer is a big fish !
Thanks, have a good day