It would take “forever” to file charges against 19,515 cabbies, Mayor Bloomberg said yesterday in defense of the city’s decision not to pursue thousands accused of overcharging passengers.

The Post reported yesterday that the Taxi & Limousine Commission had decided to give a pass to nearly 90 percent of the 21,189 cabbies ensnared in the 2010 scandal.

“What we’ve chosen to do is the rational thing . . . You go after the most egregious cases — and those cases, incidentally, are the ones you’re most likely to win — and hopefully that sends a message to everyone.”