Britney Spears (Jason Merritt/GETTY IMAGES)

Britney Spears will not stick around to mentor X-testants on the third season of the Fox singing competition “The X Factor.”

No surprise here.

Spears was being paid $15 mill-ish to play a mentor on the show. That would have been a small price to pay had she goosed the ratings of “X Factor,” which in its first season achieved only half the crowd that creator Simon Cowell had promised.

But Brit failed to deliver, the ratings tumbled even further in the second season, and the show got clobbered by NBC’s singing-competition series, “The Voice.”

Word of Spears’s exit surfaced less than 48 hours after Fox Entertainment Chairman Kevin Reilly told TV critics that Spears did a good job on the show and that the network was on board with bringing her back for the show’s third season.

“I think Britney did a really good job,” he said at Winter TV Press Tour 2013. “People remain fascinated with her and always will be. She tucked in really nicely on that bench.”

Those remarks left at least one TV columnist wondering what show Reilly had been watching. Despite her fame and history of bizarr-o behavior, Britbrit’s time on “X” was most notable for her apparent boredom and limited vocabulary — “awesome” and one or two other words.

That was enormously disappointing to viewers, who’d naturally hoped to see the pop star engage in more of her famed erratic behavior.

In exiting, Bribrit is joining L.A. Reid, who has also bailed on the third season. He said that he has to get back to his other career: finding music talent in the real world.

This will be the second time that “X” has replaced two mentors on the show. At the end of the first season, Cowell dumped Paula Abdul and Nicole Scherzinger, as well as host Steve Jones, citing the disappointing ratings — numbers that he’d now be happy to get.

In addition to Spears, the show this past season added Demi Lovato and the new co-hosts: veteran Mario Lopez was joined by Khloe Kardashian, who every week read every line off cue cards as if she were taking the eye test at the DMV.