Quentin Tarantino continues his tour of “disreputable” movie genres with “Django Unchained.” It’s a boisterous and violent appropriation of tropes from the 1960s spaghetti Western (low-budget European cowboy movies, produced mostly in Italy and Spain) and the 1970s blaxploitation Western (often-angry revenge pictures that examined the Civil War era in general, and slavery in particular, from a post-civil rights perspective).

While the movie doesn’t take the outrageous narrative leaps of “Inglorious Basterds,” “Django” is nonetheless an intelligent thrill ride, zipping along merrily (and bloodily) until it hits the inevitable Tarantino Act 3 Lag. But even the slow bits can’t detract all that much from the wealth of trashy pleasures offered throughout.

Jamie Foxx stars as Django, a slave purchased (not without a little gunplay) by Dr. King Schultz (Christoph Waltz), whose traveling-dentist wagon is cover for Schultz’s real profession, bounty hunting. Schultz needs Django to ID his quarry — three brothers who, as it turns out, delivered a horrific whipping to Django and his wife, Broomhilda (Kerry Washington), when they tried to escape their previous owner.

Django takes to the bounty hunting business with no small enthusiasm (“Kill white folks and they pay you for it? What’s not to like?”), although he eventually does discover a pang of conscience along the way.

Still, his main priority is to find and rescue Broomhilda, with Schultz’s help, which brings them to the plantation of the decadent dandy Calvin Candie (Leonardo DiCaprio), who trains slaves to fight to the death as sport and entertainment.

As is his wont, Tarantino mixes flourishes of his favorite old movies (the jarring, rapid zooms are right out of Sergio Leone) with his own (blood sprays across every white surface imaginable in this movie, from unpicked cotton to snow drifts — it’s surprising he didn’t work in a wedding gown as well).

There are B-movie legends scattered throughout, but don’t be surprised if you miss some of them. James Russo and Franco Nero (who starred in 1966’s unrelated “Django”) are front and center, but I didn’t realize that Russ Tamblyn and Ted Neeley, among others, were in the cast until I saw the closing credits.

Foxx gives a fascinating performance — I don’t know that I’ve ever seen an ex-slave portrayed as someone with PTSD, but it makes perfect sense, given everything the character has endured. By the end of the film, he’s effectively conning white people with any number of fake identities, including that of a black slaver who’s consulting Schultz on which fighters to buy.

Some might dismiss Waltz’s utterly entertaining performance as merely a variation on his hyper-articulate and whimsically dangerous villain from “Basterds,” but that’s like complaining that Cary Grant’s characters in “My Favorite Wife” and “His Girl Friday” are too suavely similar.

Tarantino regular Samuel L. Jackson pops up toward the end as a duplicitous slave who’s more cunning and far less unctuous than he originally appears.

The real revelation here is DiCaprio, looser and funnier than he’s ever been on screen.

Turns out he’s got a knack for both comedy and villainy, and his wonderfully despicable performance here whets the appetite for future ventures in this direction.

If Tarantino has a flaw as a filmmaker, however, it’s in his sense of pacing and knowing when to leave well enough alone. The film’s first half or so crackles excitingly, establishing the characters and the plot, and developing the storyline in a way that never stops moving forward.

By the time we reach “Candie Land,” though, things slow down to a crawl, and “Django” threatens to fritter away all its good will. (It’s a testament to the strong opening that that never happens.)

Plodding through the parts that the filmmaker couldn’t bear to trim down winds up being more than worthwhile, however, for the many moments of sheer movie-going pleasure that “Django Unchained” provides. It’s a bloody treat.