Don't have a cow, man! New episodes of "The Simpsons" begin tonight - finally (7 p.m., Ch. 13).

The reason for the long delay (most other returning series debuted weeks ago) is very simple: It takes a long time to produce an animated series.In a live-action series, the writers write the script, the actors learn their lines, the actors perform their parts, the show is edited and it's on TV.

In an animated series, the writers write the script, the actors learn their lines, the actors speak their parts, the show is edited and the soundtrack is completed. Still unfinished is all the animation. For the writing, performing and animation, it's about six months from start to finish.

"It's almost impossible to lick that," said Sam Simon, one of the show's executive producers. "It just plain takes that much time. If you do everything right and you come up with every great idea, you could shave it by a few weeks. But that's it. That's what the form is."

There have been rumors periodically that "The Simpsons" has experienced tremendous production problems of late. But the producers dismiss those reports, saying it hasn't been any worse than expected.

"We did get a slightly late start this season but we're going to have 22 new episodes just like a regular TV show," Simon said.

"I think we've gotten a little better this season because last year we were working on so many shows at once before we'd ever seen the results of our labors," said James L. Brooks, another of the executive producers. "And as it turned out, our hunches were right and stuff came out the way we wanted it to. And this season, we're building on the foundation of the first season.

"So if anything, the show should be more audacious. Not only is the show trying not to repeat other shows, we're also trying not to repeat ourselves. And we've gone in some very odd but entertaining directions."

And come up with shows for this season like:

- After using a new hair restorer, Homer grows stunning new locks. He's immediately placed in the power plant's executive program, gets his own office and his own (gay) male secretary.

- A Halloween special along the lines of "Tales from the Crypt" is planned.

- Marge leads a protest against the ultra-violent "Itchy and Scratchy" cartoons that we often see the Simpson kids watching on TV.

- A flashback to Homer and Marge in their high school days - and a revelation about why they got married.

Tonight's premiere features Bart the Underachiever - but he's not proud of it. If he fails one more history test, Bart will find himself held back in fourth grade.

You'll see Bart try. You'll see him cry. You'll even see him pray.

Bart actually agrees to teach the class nerd to be cool if the class nerd teaches him history. But Bart does his job too well - and the class nerd adopts his "who cares?" attitude all too quickly.

In typical "Simpsons" fashion, the ending isn't quite what you'd expect. And even parents worried about their children adopting Bart's "Underachiever and Proud of It" motto can watch without fear. (Not that they have much to worry about, anyway. Give kids some credit - they know this is only a cartoon.)

At any rate, "The Simpsons" are back. Aye, caramba!